feat(altair): implement lollipop-basic (#5445)

## Implementation: `lollipop-basic` - python/altair

Implements the **python/altair** version of `lollipop-basic`.

**File:** `plots/lollipop-basic/implementations/python/altair.py`

**Parent Issue:** #934

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/24956996445)*

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

plots/lollipop-basic/implementations/python/altair.py

@@ -1,14 +1,27 @@
-""" pyplots.ai
+""" anyplot.ai
 lollipop-basic: Basic Lollipop Chart
-Library: altair 6.0.0 | Python 3.13.11
-Quality: 92/100 | Created: 2025-12-23
+Library: altair 6.1.0 | Python 3.14.4
+Quality: 91/100 | Updated: 2026-04-26
 """
 
+import os
+
 import altair as alt
 import pandas as pd
 
 
-# Data - Product sales by category, sorted by value
+# Theme tokens (see prompts/default-style-guide.md "Theme-adaptive Chrome")
+THEME = os.getenv("ANYPLOT_THEME", "light")
+PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
+ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
+INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
+INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
+GRID = INK
+GRID_OPACITY = 0.10
+
+BRAND = "#009E73"  # Okabe-Ito position 1 — ALWAYS first series
+
+# Data — Product sales by category, sorted by value
 categories = [
     "Electronics",
     "Clothing",
@@ -24,45 +37,62 @@
 values = [425000, 312000, 287000, 234000, 198000, 176000, 152000, 134000, 118000, 95000]
 
 df = pd.DataFrame({"category": categories, "value": values})
-
-# Sort by value descending for better readability
 df = df.sort_values("value", ascending=False).reset_index(drop=True)
 
-# Create stems (vertical lines from baseline to value)
+# Stems (vertical lines from baseline to value)
 stems = (
     alt.Chart(df)
-    .mark_rule(color="#306998", strokeWidth=3)
+    .mark_rule(color=BRAND, strokeWidth=4)
     .encode(
-        x=alt.X(
-            "category:N", sort="-y", title="Category", axis=alt.Axis(labelFontSize=16, titleFontSize=20, labelAngle=-45)
-        ),
-        y=alt.Y("value:Q", title="Sales ($)", axis=alt.Axis(labelFontSize=16, titleFontSize=20)),
+        x=alt.X("category:N", sort="-y", title="Category", axis=alt.Axis(labelAngle=-35)),
+        y=alt.Y("value:Q", title="Sales (USD)", axis=alt.Axis(format="$,.0f")),
     )
 )
 
-# Create dots at the top of each stem
+# Dots at the top of each stem
 dots = (
     alt.Chart(df)
-    .mark_circle(color="#306998", size=400)
+    .mark_circle(color=BRAND, size=550, opacity=1, stroke=PAGE_BG, strokeWidth=2)
     .encode(
         x=alt.X("category:N", sort="-y"),
         y=alt.Y("value:Q"),
-        tooltip=["category:N", alt.Tooltip("value:Q", format="$,.0f")],
+        tooltip=[alt.Tooltip("category:N", title="Category"), alt.Tooltip("value:Q", title="Sales", format="$,.0f")],
     )
 )
 
-# Combine stems and dots
 chart = (
     (stems + dots)
     .properties(
-        width=1600, height=900, title=alt.Title("lollipop-basic · altair · pyplots.ai", fontSize=28, anchor="middle")
+        width=1600,
+        height=900,
+        background=PAGE_BG,
+        title=alt.Title(
+            "Product Sales by Category · lollipop-basic · altair · anyplot.ai",
+            fontSize=28,
+            anchor="start",
+            color=INK,
+            offset=20,
+        ),
     )
-    .configure_axis(labelFontSize=16, titleFontSize=20, grid=True, gridOpacity=0.3)
-    .configure_view(strokeWidth=0)
+    .configure_view(fill=PAGE_BG, stroke=None)
+    .configure_axis(
+        domainColor=INK_SOFT,
+        domainWidth=1,
+        tickColor=INK_SOFT,
+        gridColor=GRID,
+        gridOpacity=GRID_OPACITY,
+        gridWidth=1,
+        labelColor=INK_SOFT,
+        labelFontSize=18,
+        titleColor=INK,
+        titleFontSize=22,
+        titlePadding=18,
+    )
+    .configure_axisX(grid=False, labelPadding=8)
+    .configure_axisY(grid=True, labelPadding=8)
+    .configure_title(color=INK, fontWeight="bold")
+    .configure_legend(fillColor=ELEVATED_BG, strokeColor=INK_SOFT, labelColor=INK_SOFT, titleColor=INK)
 )
 
-# Save as PNG (scale_factor=3 to get 4800x2700)
-chart.save("plot.png", scale_factor=3.0)
-
-# Save as HTML for interactive version
-chart.save("plot.html")
+chart.save(f"plot-{THEME}.png", scale_factor=3.0)
+chart.save(f"plot-{THEME}.html")