feat(pygal): implement pie-basic (#1362)

## Implementation: `pie-basic` - pygal

Implements the **pygal** version of `pie-basic`.

**File:** `plots/pie-basic/implementations/pygal.py`

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20447776548)*

---------

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/pie-basic/implementations/pygal.py

@@ -1,7 +1,7 @@
 """ pyplots.ai
 pie-basic: Basic Pie Chart
 Library: pygal 3.1.0 | Python 3.13.11
-Quality: 92/100 | Created: 2025-12-14
+Quality: 91/100 | Created: 2025-12-23
 """
 
 import pygal
@@ -12,7 +12,7 @@
 categories = ["Product A", "Product B", "Product C", "Product D", "Product E"]
 values = [35, 25, 20, 12, 8]
 
-# Custom style for 4800x2700 px
+# Custom style for 3600x3600 px (square format for pie chart)
 custom_style = Style(
     background="white",
     plot_background="white",
@@ -30,8 +30,8 @@
 
 # Create pie chart
 chart = pygal.Pie(
-    width=4800,
-    height=2700,
+    width=3600,
+    height=3600,
     style=custom_style,
     title="pie-basic · pygal · pyplots.ai",
     inner_radius=0,

plots/pie-basic/metadata/pygal.yaml

@@ -1,17 +1,26 @@
 library: pygal
 specification_id: pie-basic
-created: 2025-12-14 08:44:13+00:00
-updated: 2025-12-14 08:44:13+00:00
+created: '2025-12-23T00:35:27Z'
+updated: '2025-12-23T00:38:26Z'
 generated_by: claude-opus-4-5-20251101
-workflow_run: 20205391737
-issue: 678
+workflow_run: 20447776548
+issue: 0
 python_version: 3.13.11
 library_version: 3.1.0
 preview_url: https://storage.googleapis.com/pyplots-images/plots/pie-basic/pygal/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/pie-basic/pygal/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/pie-basic/pygal/plot.html
-quality_score: 92
+quality_score: 91
 review:
-  strengths: []
-  weaknesses: []
-  improvements: []
+  strengths:
+  - Clean, readable code following KISS principles with clear section comments
+  - Excellent color palette with good contrast and colorblind accessibility
+  - Proper use of pygal Style class for comprehensive customization
+  - Percentage labels are well-positioned and clearly readable inside slices
+  - Correct title format following pyplots.ai conventions
+  - Generates both PNG and HTML outputs for flexibility
+  weaknesses:
+  - Legend at bottom appears relatively small compared to the pie chart; could increase
+    legend_font_size for better readability
+  - Missing slight explosion for emphasis on key slice as suggested in the specification
+    notes