feat(ci): add automated codebase pie chart update workflow

Add GitHub Actions workflow to automatically generate and update codebase structure pie chart every two months.

The workflow:

- Runs on schedule (1st day of every 2nd month at 4:00 UTC)
- Triggers on manual dispatch and relevant code changes
- Uses Ubuntu runner with Python 3.13 and UV package manager
- Generates PNG and SVG pie charts showing code distribution
- Creates pull requests only when chart files change
- Includes comprehensive PR descriptions with metrics context

This automation ensures the codebase visualization stays current
with project evolution and provides regular snapshots of code health
metrics including test coverage ratios, documentation ratios,
and generated vs hand-written code proportions.

Author: amilcarlucas

.github/workflows/update_codebase_chart.yml

@@ -0,0 +1,96 @@
+name: Update Codebase Pie Chart
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 4 1 */2 *'  # Run at 4:00 UTC on the 1st day of every 2nd month
+  push:
+    branches:
+      - master
+    paths:
+      - 'scripts/generate_codebase_pie_chart.py'
+      - 'ardupilot_methodic_configurator/**/*.py'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  update-chart:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write       # for creating branches and commits
+      pull-requests: write  # for creating PRs
+
+    env:
+      CHART_CHANGED: false
+
+    strategy:
+      matrix:
+        python-version: ['3.13']
+
+    steps:
+      - name: Harden the runner (Audit all outbound calls)
+        uses: step-security/harden-runner@ec9f2d5744a09debf3a187a3f4f675c53b671911 # v2.13.0
+        with:
+          egress-policy: audit
+
+      - name: Checkout
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+
+      # https://docs.astral.sh/uv/guides/integration/github/
+      - name: Install uv and set the python version
+        uses: astral-sh/setup-uv@557e51de59eb14aaaba2ed9621916900a91d50c6 # v6.6.1
+        with:
+          python-version: ${{ matrix.python-version }}
+          activate-environment: true
+
+      - name: Install dependencies
+        # required by generate_codebase_pie_chart.py
+        run: |
+            uv pip install .[dev]
+
+      - name: Generate codebase pie chart
+        run: python scripts/generate_codebase_pie_chart.py
+
+      - name: Check for changes and stage them
+        run: |
+          git add images/codebase_structure_pie_chart.png
+          git add images/codebase_structure_pie_chart.svg
+          if [[ -n "$(git status --porcelain)" ]]; then
+            echo "CHART_CHANGED=true" >> $GITHUB_ENV
+          else
+            echo "No changes to commit"
+          fi
+
+      - name: Create Pull Request
+        if: env.CHART_CHANGED == 'true'
+        uses: peter-evans/create-pull-request@271a8d0340265f705b14b6d32b9829c1cb33d45e # v7.0.8
+        with:
+          labels: documentation, automated-pr, codebase-analysis
+          token: ${{ secrets.GITHUB_TOKEN }}
+          branch: update-codebase-chart
+          title: "Update codebase structure pie chart"
+          commit-message: "docs(codebase pie chart): Update codebase structure pie chart with latest metrics"
+          body: |
+            This PR updates the codebase structure pie chart with the latest code metrics.
+
+            The chart shows the distribution of code lines across different categories:
+            - Test Code (Python)
+            - Core Application Code (Python, hand-written)
+            - Generated Code (Python, auto-generated)
+            - Utility Scripts (Python + shell)
+            - Documentation (Markdown files)
+            - Configuration (JSON files)
+
+            Changes were automatically generated by the `scripts/generate_codebase_pie_chart.py` script.
+
+            The updated chart reflects the current state of the codebase and helps track:
+            - Test coverage ratios
+            - Documentation-to-code ratios
+            - Generated vs. hand-written code proportions
+            - Overall project health metrics
+          delete-branch: true