feat(plotly): implement facet-grid (#6515)

## Implementation: `facet-grid` - python/plotly

Implements the **python/plotly** version of `facet-grid`.

**File:** `plots/facet-grid/implementations/python/plotly.py`

**Parent Issue:** #2696

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/25776278040)*

---------

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/facet-grid/implementations/python/plotly.py

@@ -1,27 +1,34 @@
-""" pyplots.ai
+""" anyplot.ai
 facet-grid: Faceted Grid Plot
-Library: plotly 6.5.0 | Python 3.13.11
-Quality: 91/100 | Created: 2025-12-30
+Library: plotly 6.7.0 | Python 3.13.13
+Quality: 92/100 | Updated: 2026-05-13
 """
 
+import os
+
 import numpy as np
 import pandas as pd
 import plotly.express as px
 
 
-# Data - Create realistic dataset for faceted visualization
+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 = "rgba(26,26,23,0.10)" if THEME == "light" else "rgba(240,239,232,0.10)"
+BRAND = "#009E73"
+
+# Data
 np.random.seed(42)
 
-# Product performance data across regions and quarters
 regions = ["North", "South", "East", "West"]
 quarters = ["Q1", "Q2", "Q3", "Q4"]
 
 data = []
 for region in regions:
     for quarter in quarters:
-        # Generate 15 data points per region-quarter combination
         n = 15
-        # Base values vary by region and quarter
         base_sales = {"North": 80, "South": 60, "East": 70, "West": 75}
         quarter_effect = {"Q1": 0, "Q2": 10, "Q3": 5, "Q4": 15}
 
@@ -45,30 +52,31 @@
 
 df = pd.DataFrame(data)
 
-# Create faceted scatter plot
-# Using single color since Region is already encoded by facet rows
+# Plot
 fig = px.scatter(df, x="Marketing Spend ($K)", y="Sales ($K)", facet_row="Region", facet_col="Quarter")
 
-# Update layout for large canvas
+# Style
 fig.update_layout(
-    title=dict(text="facet-grid · plotly · pyplots.ai", font=dict(size=32), x=0.5, xanchor="center"),
-    font=dict(size=16),
-    template="plotly_white",
+    title={"text": "facet-grid · plotly · anyplot.ai", "font": {"size": 28, "color": INK}, "x": 0.5, "xanchor": "center"},
+    paper_bgcolor=PAGE_BG,
+    plot_bgcolor=PAGE_BG,
+    font={"color": INK},
     showlegend=False,
-    margin=dict(l=80, r=80, t=100, b=80),
+    margin={"l": 80, "r": 80, "t": 100, "b": 80},
 )
 
-# Update axes for all facets
-fig.update_xaxes(title_font=dict(size=20), tickfont=dict(size=16), gridcolor="rgba(0,0,0,0.1)", gridwidth=1)
+fig.update_xaxes(
+    title_font={"size": 22, "color": INK}, tickfont={"size": 18, "color": INK_SOFT}, gridcolor=GRID, linecolor=INK_SOFT
+)
 
-fig.update_yaxes(title_font=dict(size=20), tickfont=dict(size=16), gridcolor="rgba(0,0,0,0.1)", gridwidth=1)
+fig.update_yaxes(
+    title_font={"size": 22, "color": INK}, tickfont={"size": 18, "color": INK_SOFT}, gridcolor=GRID, linecolor=INK_SOFT
+)
 
-# Update facet labels (annotations)
-fig.for_each_annotation(lambda a: a.update(font=dict(size=18)))
+fig.for_each_annotation(lambda a: a.update(font={"size": 18, "color": INK}))
 
-# Update markers with consistent color for visibility
-fig.update_traces(marker=dict(size=12, opacity=0.8, color="#306998", line=dict(width=1, color="white")))
+fig.update_traces(marker={"size": 16, "opacity": 0.8, "color": BRAND, "line": {"width": 1, "color": PAGE_BG}})
 
-# Save as PNG and HTML
-fig.write_image("plot.png", width=1600, height=900, scale=3)
-fig.write_html("plot.html", include_plotlyjs="cdn")
+# Save
+fig.write_image(f"plot-{THEME}.png", width=1600, height=900, scale=3)
+fig.write_html(f"plot-{THEME}.html", include_plotlyjs="cdn")