docs(examples): describe the carousel that shipped, and scale the boxes with the type

The prose still described the first commit: five slides at 1080x1350, where
adding the social card made it six at 1280x1600. Class javadoc and the method
comment both said five.

The widening scaled the type helpers but left the gaps, corner radii, accent
bars and stroke widths at their 1080-era values, so "the slides keep their
proportions" was true of the text and not of the boxes around it. They take the
same ratio now, and the constant's javadoc says which lengths it applies to
rather than leaving the next reader to guess.

The opening slide's centring spacer is floored at zero: a card taller than the
page would have asked for a negative height instead of simply filling the frame.

Author: DemchaAV

examples/src/main/java/com/demcha/examples/flagships/LinkedInCarouselExample.java

@@ -30,13 +30,14 @@
 import java.util.Locale;
 
 /**
- * A five-slide carousel sized for a LinkedIn document post, composed through the
+ * A six-slide carousel sized for a LinkedIn document post, composed through the
  * canonical DSL and rendered by the engine it describes.
  *
- * <p>Portrait 1080&times;1350 (4:5), which is the tallest frame LinkedIn shows
- * without cropping and therefore the most readable on a phone. Type is sized for
- * that phone, not for a desktop preview: the smallest text on a slide is 18pt at
- * a 1080-wide page, so it survives the reduction.</p>
+ * <p>Portrait 1280&times;1600 (4:5), which is the tallest frame LinkedIn shows
+ * without cropping and therefore the most readable on a phone. The width is set
+ * by the opening slide: it carries {@link SocialCardExample}'s card at native
+ * size rather than a scaled copy. Type is sized for that phone, not for a
+ * desktop preview.</p>
  *
  * <p>Every figure is read at render time — the version from the filtered
  * {@code banner.properties}, the comparative timings from the committed
@@ -59,8 +60,10 @@ public final class LinkedInCarouselExample {
 
     /**
      * Everything below was drawn against a 1080-wide page. Rather than restate
-     * every size, the type helpers scale by this ratio, so the slides keep their
-     * proportions on the wider frame.
+     * every size, the type helpers and the box metrics scale by this ratio, so
+     * the slides keep their proportions on the wider frame. Apply it to any
+     * length that was eyeballed against the narrower page; the only literals
+     * that stay absolute are ones derived from the page itself.
      */
     private static final double SCALE = PAGE_WIDTH / 1080.0;
 
@@ -172,7 +175,7 @@ private static DocumentSession session(Path outputFile) {
     }
 
     /**
-     * Composes all five slides.
+     * Composes all six slides.
      *
      * @param document the open session to compose into
      */
@@ -213,8 +216,10 @@ static void compose(DocumentSession document) {
 
     private static void cardSlide(SectionBuilder slide) {
         slide.spacing(0);
-        slide.addSpacer(sp -> sp.width(PAGE_WIDTH)
-                .height((PAGE_HEIGHT - SocialCardExample.CARD_HEIGHT) / 2));
+        // Floored: a card taller than the page would otherwise ask for a
+        // negative spacer rather than simply filling the frame.
+        double bleed = Math.max(0, (PAGE_HEIGHT - SocialCardExample.CARD_HEIGHT) / 2);
+        slide.addSpacer(sp -> sp.width(PAGE_WIDTH).height(bleed));
         slide.add(SocialCardExample.scene());
     }
 
@@ -237,7 +242,7 @@ private static void cover(SectionBuilder slide) {
                 .lineSpacing(1.45)
                 .margin(DocumentInsets.zero()));
         slide.addRow("Formats", row -> {
-            row.spacing(14).evenWeights();
+            row.spacing(14 * SCALE).evenWeights();
             formatChip(row, "PDF", "fixed layout", "PDFBox", MINT);
             formatChip(row, "PPTX", "fixed layout", "Apache POI", VIOLET_LIGHT);
             formatChip(row, "DOCX", "semantic", "Apache POI", AMBER);
@@ -282,15 +287,15 @@ private static void numbersSlide(SectionBuilder slide, EngineDeckData.BenchRun b
         slide.addParagraph(p -> p
                 .text("Average render latency, milliseconds — lower is faster.")
                 .textStyle(body(30, ON_DARK_MUTED))
-                .margin(DocumentInsets.bottom(10)));
+                .margin(DocumentInsets.bottom(10 * SCALE)));
 
         slide.addSection("Chart", card -> card
-                .softPanel(SURFACE, 20, 26)
-                .stroke(DocumentStroke.of(LINE, 1))
+                .softPanel(SURFACE, 20 * SCALE, 26 * SCALE)
+                .stroke(DocumentStroke.of(LINE, 1 * SCALE))
                 .chart(latencyChart(bench), latencyStyle()));
 
         slide.addRow("Ratios", row -> {
-            row.spacing(14).evenWeights();
+            row.spacing(14 * SCALE).evenWeights();
             ratio(row, times(bench.timeMs("iText 9", TIER) / bench.timeMs("GraphCompose", TIER)),
                     "faster than iText 9", VIOLET_LIGHT);
             ratio(row, times(bench.heapMb("iText 9", TIER) / bench.heapMb("GraphCompose", TIER)),
@@ -339,9 +344,9 @@ private static void closeSlide(SectionBuilder slide) {
                 .textStyle(headline(132))
                 .margin(DocumentInsets.zero()));
         slide.addSection("Coords", card -> {
-            card.softPanel(SURFACE, 20, CARD_PAD)
-                    .stroke(DocumentStroke.of(LINE, 1))
-                    .spacing(4);
+            card.softPanel(SURFACE, 20 * SCALE, CARD_PAD)
+                    .stroke(DocumentStroke.of(LINE, 1 * SCALE))
+                    .spacing(4 * SCALE);
             card.addSpacer(sp -> sp.width(CARD_INNER).height(0));
             // Split on the colon rather than set in one line: the coordinate is
             // wider than the card at this size and broke mid-artifact.
@@ -362,9 +367,9 @@ private static void closeSlide(SectionBuilder slide) {
                     .margin(DocumentInsets.zero()));
         });
         slide.addSection("Snippet", card -> {
-            card.softPanel(SURFACE_2, 20, CARD_PAD)
-                    .accentLeft(VIOLET, 4)
-                    .spacing(2);
+            card.softPanel(SURFACE_2, 20 * SCALE, CARD_PAD)
+                    .accentLeft(VIOLET, 4 * SCALE)
+                    .spacing(2 * SCALE);
             card.addSpacer(sp -> sp.width(CARD_INNER).height(0));
             for (String line : SNIPPET) {
                 card.addParagraph(p -> p
@@ -377,7 +382,7 @@ private static void closeSlide(SectionBuilder slide) {
         slide.addParagraph(p -> p
                 .text("github.com/DemchaAV/GraphCompose")
                 .textStyle(body(46, VIOLET_LIGHT))
-                .margin(DocumentInsets.top(4)));
+                .margin(DocumentInsets.top(4 * SCALE)));
         slide.addParagraph(p -> footnote(p,
                 "Java 17+. Every slide in this carousel was composed with the library "
                 + "and rendered by its own PDF backend - the PPTX beside it comes from "
@@ -398,9 +403,9 @@ private static void point(SectionBuilder slide, String title, DocumentColor acce
         // longest line, which leaves a stack of cards with ragged right edges.
         // An even-weighted row gives every card the full content width.
         slide.addSection("Point", card -> {
-            card.softPanel(SURFACE, 26, CARD_PAD)
-                    .accentLeft(accent, 4)
-                    .spacing(6);
+            card.softPanel(SURFACE, 26 * SCALE, CARD_PAD)
+                    .accentLeft(accent, 4 * SCALE)
+                    .spacing(6 * SCALE);
             card.addSpacer(sp -> sp.width(CARD_INNER).height(0));
             card.addParagraph(p -> p
                     .text(title)
@@ -422,8 +427,8 @@ private static void formatChip(RowBuilder row, String name, String lane,
                                    String engine, DocumentColor accent) {
         row.addSection(name, card -> {
             card.softPanel(SURFACE_2, 20, 24)
-                    .stroke(DocumentStroke.of(LINE, 1))
-                    .spacing(2);
+                    .stroke(DocumentStroke.of(LINE, 1 * SCALE))
+                    .spacing(2 * SCALE);
             card.addParagraph(p -> p
                     .text(name)
                     .textStyle(DocumentTextStyle.builder()
@@ -442,15 +447,15 @@ private static void formatChip(RowBuilder row, String name, String lane,
                     .text(engine)
                     .textStyle(mono(23, DocumentColor.rgb(122, 131, 162)))
                     .align(TextAlign.CENTER)
-                    .margin(DocumentInsets.top(4)));
+                    .margin(DocumentInsets.top(4 * SCALE)));
         });
     }
 
     private static void ratio(RowBuilder row, String value, String label, DocumentColor accent) {
         row.addSection("Ratio", card -> {
-            card.softPanel(SURFACE_2, 14, 24)
-                    .accentTop(accent, 3)
-                    .spacing(2);
+            card.softPanel(SURFACE_2, 14 * SCALE, 24 * SCALE)
+                    .accentTop(accent, 3 * SCALE)
+                    .spacing(2 * SCALE);
             card.addParagraph(p -> p
                     .text(value)
                     .textStyle(DocumentTextStyle.builder()
@@ -487,7 +492,7 @@ private static ChartSpec latencyChart(EngineDeckData.BenchRun bench) {
     private static ChartStyle latencyStyle() {
         return ChartStyle.builder()
                 .seriesPaint(0, DocumentPaint.solid(VIOLET))
-                .barCornerRadius(DocumentCornerRadius.of(4))
+                .barCornerRadius(DocumentCornerRadius.of(4 * SCALE))
                 .barWidthRatio(0.5)
                 .axisTextStyle(mono(22, ON_DARK_MUTED))
                 .valueLabelTextStyle(mono(25, ON_DARK))
@@ -498,7 +503,7 @@ private static ParagraphBuilder footnote(ParagraphBuilder p, String text) {
         return p.text(text)
                 .textStyle(body(22, DocumentColor.rgb(130, 139, 170)))
                 .lineSpacing(1.4)
-                .margin(DocumentInsets.top(6));
+                .margin(DocumentInsets.top(6 * SCALE));
     }
 
     private static String times(double ratio) {