feat(highcharts): implement donut-basic (#1403)

## Implementation: `donut-basic` - highcharts

Implements the **highcharts** version of `donut-basic`.

**File:** `plots/donut-basic/implementations/highcharts.py`

---
:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/pyplots/actions/runs/20448001420)*

---------

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/donut-basic/implementations/highcharts.py

@@ -1,7 +1,7 @@
 """ pyplots.ai
 donut-basic: Basic Donut Chart
-Library: highcharts 1.10.3 | Python 3.13.11
-Quality: 95/100 | Created: 2025-12-14
+Library: highcharts unknown | Python 3.13.11
+Quality: 91/100 | Created: 2025-12-23
 """
 
 import tempfile
@@ -41,7 +41,7 @@
 
 # Title
 chart.options.title = {
-    "text": "donut-basic \u00b7 highcharts \u00b7 pyplots.ai",
+    "text": "donut-basic · highcharts · pyplots.ai",
     "style": {"fontSize": "48px", "fontWeight": "bold"},
 }
 

plots/donut-basic/metadata/highcharts.yaml

@@ -1,17 +1,24 @@
 library: highcharts
 specification_id: donut-basic
-created: 2025-12-14 10:13:32+00:00
-updated: 2025-12-14 10:13:32+00:00
+created: '2025-12-23T00:51:02Z'
+updated: '2025-12-23T01:22:13Z'
 generated_by: claude-opus-4-5-20251101
-workflow_run: 20206401194
-issue: 733
+workflow_run: 20448001420
+issue: 0
 python_version: 3.13.11
-library_version: 1.10.3
+library_version: unknown
 preview_url: https://storage.googleapis.com/pyplots-images/plots/donut-basic/highcharts/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/donut-basic/highcharts/plot_thumb.png
 preview_html: https://storage.googleapis.com/pyplots-images/plots/donut-basic/highcharts/plot.html
-quality_score: 95
+quality_score: 91
 review:
-  strengths: []
-  weaknesses: []
-  improvements: []
+  strengths:
+  - Excellent use of colorblind-safe color palette matching library guidelines
+  - Clean center annotation showing total budget with proper formatting
+  - Well-sized data labels with percentage formatting
+  - Professional appearance with good ring thickness (55% inner size)
+  - Proper Highcharts implementation with correct container setup
+  - Interactive HTML version also generated
+  weaknesses:
+  - Legend text appears slightly small relative to the chart size on the right side
+  - 'Center text could be better vertically centered (currently offset with y: 60)'