restructure workflows

.github/workflows/deploy-main-pages.yml

@@ -0,0 +1,78 @@
+name: Deploy main to GitHub Pages (stable)
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+
+jobs:
+  deploy-main-pages:
+    if: ${{ env.ENABLE_DEPLOY == 'true' && env.ACT != 'true' }}
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout (main)
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.13"
+          cache: "pip"
+          cache-dependency-path: mkdocs/requirements.txt
+
+      - name: Install dependencies
+        run: |
+          set -euo pipefail
+          pip install -r mkdocs/requirements.txt
+
+      - name: Build (MKDOCS_STRICT)
+        run: |
+          set -euo pipefail
+
+          MKDOCS_STRICT="${MKDOCS_STRICT:-true}"
+          STRICT_FLAG=""
+          if [ "${MKDOCS_STRICT}" = "true" ]; then
+            STRICT_FLAG="--strict"
+          fi
+
+          OFFLINE=true mkdocs build ${STRICT_FLAG} -f mkdocs/mkdocs.yml -d site_build
+
+      - name: Checkout gh-pages branch
+        run: |
+          set -euo pipefail
+          git fetch origin gh-pages:gh-pages || true
+          if git show-ref --verify --quiet refs/heads/gh-pages; then
+            git switch gh-pages
+          else
+            git switch --orphan gh-pages
+            rm -rf ./*
+            git config user.name "github-actions[bot]"
+            git config user.email "github-actions[bot]@users.noreply.github.com"
+            git commit --allow-empty -m "Initialize gh-pages"
+          fi
+
+      - name: Publish stable site to root (preserve rc/)
+        run: |
+          set -euo pipefail
+
+          mkdir -p _keep
+          if [ -d rc ]; then cp -a rc _keep/; fi
+
+          rm -rf ./*
+          if [ -d _keep/rc ]; then mv _keep/rc ./rc; fi
+          rm -rf _keep
+
+          cp -a ../site_build/. .
+
+          git add -A
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git commit -m "Deploy stable site from main" || echo "No changes to commit"
+          git push origin gh-pages