feat(seaborn): implement ecdf-basic (#9483)

## Implementation: `ecdf-basic` - python/seaborn

Implements the **python/seaborn** version of `ecdf-basic`.

**File:** `plots/ecdf-basic/implementations/python/seaborn.py`

**Parent Issue:** #976

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/28160225103)*

---------

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

Author: github-actions[bot]

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

@@ -1,7 +1,7 @@
 """ anyplot.ai
 ecdf-basic: Basic ECDF Plot
-Library: seaborn 0.13.2 | Python 3.14.4
-Quality: 88/100 | Updated: 2026-04-24
+Library: seaborn 0.13.2 | Python 3.13.14
+Quality: 90/100 | Updated: 2026-06-25
 """
 
 import os
@@ -10,13 +10,16 @@
 import seaborn as sns
 
 
-# Theme tokens
+# Theme tokens — Imprint palette + 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"
-BRAND = "#009E73"  # Okabe-Ito position 1
+INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
+
+# Imprint categorical palette — positions 1, 2, 3 (Adelie, Chinstrap, Gentoo)
+IMPRINT_PALETTE = ["#009E73", "#C475FD", "#4467A3"]
 
 sns.set_theme(
     style="ticks",
@@ -29,35 +32,54 @@
         "xtick.color": INK_SOFT,
         "ytick.color": INK_SOFT,
         "grid.color": INK,
-        "grid.alpha": 0.10,
+        "grid.alpha": 0.12,
         "legend.facecolor": ELEVATED_BG,
         "legend.edgecolor": INK_SOFT,
     },
 )
 
-# Data - real-world sample: penguin flipper lengths
-penguins = sns.load_dataset("penguins").dropna(subset=["flipper_length_mm"])
+# Data — penguin flipper lengths by species (deterministic real-world dataset)
+penguins = sns.load_dataset("penguins").dropna(subset=["flipper_length_mm", "species"])
 
-# Plot
-fig, ax = plt.subplots(figsize=(16, 9), facecolor=PAGE_BG)
+# Plot — multi-hue ecdfplot shows distribution comparison across species
+fig, ax = plt.subplots(figsize=(8, 4.5), dpi=400, facecolor=PAGE_BG)
 ax.set_facecolor(PAGE_BG)
 
-sns.ecdfplot(data=penguins, x="flipper_length_mm", ax=ax, linewidth=3.5, color=BRAND)
+sns.ecdfplot(data=penguins, x="flipper_length_mm", hue="species", palette=IMPRINT_PALETTE, linewidth=2.5, ax=ax)
+
+# Percentile reference lines for direct reading of Q1 / median / Q3
+for p in (0.25, 0.50, 0.75):
+    ax.axhline(p, color=INK_MUTED, linewidth=0.7, linestyle="--", alpha=0.55, zorder=0)
 
 # Style
-ax.set_xlabel("Flipper Length (mm)", fontsize=20, color=INK)
-ax.set_ylabel("Cumulative Proportion", fontsize=20, color=INK)
-ax.set_title("Penguin Flipper Lengths · ecdf-basic · seaborn · anyplot.ai", fontsize=24, fontweight="medium", color=INK)
-ax.tick_params(axis="both", labelsize=16, colors=INK_SOFT)
+title = "Penguin Flipper Lengths · ecdf-basic · python · seaborn · anyplot.ai"
+n = len(title)
+title_fontsize = round(12 * 67 / n) if n > 67 else 12
+ax.set_title(title, fontsize=title_fontsize, fontweight="medium", color=INK)
+ax.set_xlabel("Flipper Length (mm)", fontsize=10, color=INK)
+ax.set_ylabel("Cumulative Proportion", fontsize=10, color=INK)
+ax.tick_params(axis="both", labelsize=8, colors=INK_SOFT)
 ax.set_ylim(0, 1)
+ax.set_yticks([0, 0.25, 0.50, 0.75, 1.0])
 
 ax.spines["top"].set_visible(False)
 ax.spines["right"].set_visible(False)
 for side in ("left", "bottom"):
     ax.spines[side].set_color(INK_SOFT)
 
-ax.grid(True, axis="both", alpha=0.10, linewidth=0.8, color=INK)
+ax.yaxis.grid(True, alpha=0.12, linewidth=0.8, color=INK)
 ax.set_axisbelow(True)
 
-plt.tight_layout()
-plt.savefig(f"plot-{THEME}.png", dpi=300, bbox_inches="tight", facecolor=PAGE_BG)
+# Style the auto-generated legend
+legend = ax.get_legend()
+if legend:
+    legend.get_frame().set_facecolor(ELEVATED_BG)
+    legend.get_frame().set_edgecolor(INK_SOFT)
+    for text in legend.get_texts():
+        text.set_color(INK_SOFT)
+        text.set_fontsize(8)
+    legend.set_title("Species", prop={"size": 8, "weight": "medium"})
+    legend.get_title().set_color(INK_SOFT)
+
+# Save — bbox_inches must stay default (None) to preserve exact figsize × dpi canvas
+plt.savefig(f"plot-{THEME}.png", dpi=400, facecolor=PAGE_BG)