feat(letsplot): implement box-grouped (#5996)

## Implementation: `box-grouped` - python/letsplot

Implements the **python/letsplot** version of `box-grouped`.

**File:** `plots/box-grouped/implementations/python/letsplot.py`

**Parent Issue:** #2017

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/25535090344)*

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>

Author: github-actions[bot]

plots/box-grouped/implementations/python/letsplot.py

@@ -1,14 +1,19 @@
-""" pyplots.ai
+""" anyplot.ai
 box-grouped: Grouped Box Plot
-Library: letsplot 4.8.2 | Python 3.13.11
-Quality: 92/100 | Created: 2025-12-25
+Library: letsplot 4.9.0 | Python 3.13.13
+Quality: 91/100 | Updated: 2026-05-08
 """
 
+import os
+import shutil
+
 import numpy as np
 import pandas as pd
 from lets_plot import (
     LetsPlot,
     aes,
+    element_line,
+    element_rect,
     element_text,
     geom_boxplot,
     ggplot,
@@ -23,6 +28,15 @@
 
 LetsPlot.setup_html()
 
+# 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"
+
+OKABE_ITO = ["#009E73", "#D55E00", "#0072B2"]
+
 # Data: Employee performance scores by department and experience level
 np.random.seed(42)
 
@@ -33,22 +47,19 @@
 for dept in departments:
     for exp in experience_levels:
         n = 40
-        # Create realistic distributions with variation
         if exp == "Junior":
-            base = 60 + np.random.choice([0, 5, 10])
+            base = 50 + np.random.choice([0, 5, 10])
             spread = 12
         elif exp == "Mid-Level":
-            base = 72 + np.random.choice([0, 3, 6])
+            base = 60 + np.random.choice([0, 3, 6])
             spread = 10
-        else:  # Senior
-            base = 82 + np.random.choice([0, 2, 4])
+        else:
+            base = 72 + np.random.choice([0, 2, 4])
             spread = 8
 
-        # Add department-specific variation
         dept_offset = {"Engineering": 3, "Marketing": 0, "Sales": -2, "Operations": 1}[dept]
         values = np.random.normal(base + dept_offset, spread, n)
 
-        # Add some outliers for boxplot visualization
         if np.random.random() > 0.5:
             outlier_low = base - 3 * spread + np.random.randn(2) * 2
             outlier_high = base + 3 * spread + np.random.randn(2) * 2
@@ -58,34 +69,35 @@
             data.append({"Department": dept, "Experience": exp, "Performance Score": v})
 
 df = pd.DataFrame(data)
-
-# Ensure proper ordering
 df["Experience"] = pd.Categorical(df["Experience"], categories=experience_levels, ordered=True)
 df["Department"] = pd.Categorical(df["Department"], categories=departments, ordered=True)
 
 # Plot
 plot = (
     ggplot(df, aes(x="Department", y="Performance Score", fill="Experience"))
     + geom_boxplot(alpha=0.85, outlier_size=3, outlier_alpha=0.7, width=0.7)
-    + scale_fill_manual(values=["#306998", "#FFD43B", "#4CAF50"])
-    + labs(
-        title="box-grouped · letsplot · pyplots.ai", x="Department", y="Performance Score (%)", fill="Experience Level"
-    )
+    + scale_fill_manual(values=OKABE_ITO)
+    + labs(title="box-grouped · letsplot · anyplot.ai", x="Department", y="Performance Score", fill="Experience Level")
     + theme_minimal()
     + theme(
-        plot_title=element_text(size=28, face="bold"),
-        axis_title=element_text(size=22),
-        axis_text=element_text(size=18),
-        axis_text_x=element_text(size=18),
-        legend_title=element_text(size=20),
-        legend_text=element_text(size=18),
+        plot_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
+        panel_background=element_rect(fill=PAGE_BG),
+        panel_grid_major=element_line(color=INK_SOFT, size=0.3),
+        plot_title=element_text(size=24, face="bold", color=INK),
+        axis_title=element_text(size=20, color=INK),
+        axis_text=element_text(size=16, color=INK_SOFT),
+        legend_background=element_rect(fill=ELEVATED_BG, color=INK_SOFT),
+        legend_title=element_text(size=16, color=INK),
+        legend_text=element_text(size=16, color=INK_SOFT),
         legend_position="right",
     )
     + ggsize(1600, 900)
 )
 
-# Save as PNG (scale 3x for 4800x2700 px)
-ggsave(plot, "plot.png", path=".", scale=3)
+# Save
+ggsave(plot, f"plot-{THEME}.png", scale=3)
+ggsave(plot, f"plot-{THEME}.html")
 
-# Save as HTML for interactivity
-ggsave(plot, "plot.html", path=".")
+# Move files from lets-plot-images to current directory
+shutil.move(f"lets-plot-images/plot-{THEME}.png", f"plot-{THEME}.png")
+shutil.move(f"lets-plot-images/plot-{THEME}.html", f"plot-{THEME}.html")