feat(letsplot): implement ecdf-basic

Regen from quality 87. Addressed:
- Canvas: ggsize(800, 450) + scale=4 → exact 3200×1800 (was ggsize(1600, 900) + scale=3 → 4800×2700)
- Title: fixed to 3-part format "ecdf-basic · python · letsplot · anyplot.ai" (removed descriptive prefix, added language token)
- Grid opacity: pre-blended #D8D7D0/#3A3A36 at ~15% opacity (was #C9C7C1/#565551 at ~22%)
- Font sizes: aligned to letsplot.md canonical 16/12/10 pt at scale=4 (was 24/20/16 at wrong scale)
- LM-02: added layer_tooltips() for interactive HTML response time display

Author: github-actions[bot]

plots/ecdf-basic/implementations/python/letsplot.py

@@ -1,7 +1,7 @@
-""" anyplot.ai
+"""anyplot.ai
 ecdf-basic: Basic ECDF Plot
-Library: letsplot 4.9.0 | Python 3.14.4
-Quality: 87/100 | Updated: 2026-04-24
+Library: letsplot | Python 3.14
+Quality: pending | Created: 2026-06-25
 """
 
 import os
@@ -18,6 +18,7 @@
     ggplot,
     ggsize,
     labs,
+    layer_tooltips,
     scale_y_continuous,
     stat_ecdf,
     theme,
@@ -31,44 +32,47 @@
 # Theme tokens
 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 = "#C9C7C1" if THEME == "light" else "#565551"
+# Imprint palette — grid at ~15% opacity, pre-blended with PAGE_BG
+GRID = "#D8D7D0" if THEME == "light" else "#3A3A36"
 BRAND = "#009E73"
 
-# Data — Web service response times (ms) with mixed distribution
+# Data — web service response times (ms) with bimodal distribution
 np.random.seed(42)
 response_times = np.concatenate(
     [np.random.exponential(scale=50, size=150), np.random.normal(loc=200, scale=30, size=50)]
 )
 df = pd.DataFrame({"response_time": response_times})
 
-# Plot — ECDF using stat_ecdf with step geometry
+# Title — 3-part format, 44 chars (< 67 baseline, no scaling needed)
+title = "ecdf-basic · python · letsplot · anyplot.ai"
+
+# Plot — ECDF step function with interactive tooltips (lets-plot HTML capability)
 plot = (
     ggplot(df, aes(x="response_time"))
-    + stat_ecdf(geom="step", color=BRAND, size=2)
-    + labs(
-        x="Response Time (ms)",
-        y="Cumulative Proportion",
-        title="Web Service Response Times · ecdf-basic · letsplot · anyplot.ai",
+    + stat_ecdf(
+        geom="step", color=BRAND, size=1.5, tooltips=layer_tooltips().line("Response Time: @response_time{,.0f} ms")
     )
+    + labs(x="Response Time (ms)", y="Cumulative Proportion", title=title)
     + scale_y_continuous(limits=[0, 1], breaks=[0, 0.25, 0.5, 0.75, 1.0])
-    + ggsize(1600, 900)
+    + ggsize(800, 450)
     + theme_minimal()
     + theme(
         plot_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
         panel_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
-        legend_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
-        panel_grid_major=element_line(color=GRID, size=0.6),
+        legend_background=element_rect(fill=ELEVATED_BG, color=INK_SOFT),
+        panel_grid_major=element_line(color=GRID, size=0.5),
         panel_grid_minor=element_blank(),
         axis_line=element_line(color=INK_SOFT, size=0.6),
         axis_ticks=element_line(color=INK_SOFT, size=0.5),
-        axis_text=element_text(size=16, color=INK_SOFT),
-        axis_title=element_text(size=20, color=INK),
-        plot_title=element_text(size=24, color=INK),
+        axis_text=element_text(size=10, color=INK_SOFT),
+        axis_title=element_text(size=12, color=INK),
+        plot_title=element_text(size=16, color=INK),
     )
 )
 
 # Save
-ggsave(plot, filename=f"plot-{THEME}.png", path=".", scale=3)
+ggsave(plot, filename=f"plot-{THEME}.png", path=".", scale=4)
 ggsave(plot, filename=f"plot-{THEME}.html", path=".")