ci: add auto-merge workflow for docs-only PRs

Automatically approves and merges PRs to main when all changed
files are markdown (.md), reducing manual review overhead for
documentation updates.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitea/workflows/auto-merge-docs.yml

@@ -0,0 +1,62 @@
+name: Auto-merge docs-only PRs
+
+on:
+  pull_request:
+    branches: [main]
+    types: [opened, synchronize]
+
+jobs:
+  auto-merge-docs:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check if all changes are markdown
+        id: check
+        env:
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+        run: |
+          PR_NUMBER=${{ github.event.pull_request.number }}
+          API_URL="${{ github.server_url }}/api/v1/repos/${{ github.repository }}/pulls/${PR_NUMBER}/files"
+
+          FILES=$(curl -sf -H "Authorization: token ${GITEA_TOKEN}" "${API_URL}" | jq -r '.[].filename')
+
+          if [ -z "$FILES" ]; then
+            echo "No files found in PR"
+            echo "docs_only=false" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+
+          echo "Changed files:"
+          echo "$FILES"
+
+          DOCS_ONLY=true
+          while IFS= read -r file; do
+            if [[ ! "$file" =~ \.md$ ]]; then
+              echo "Non-markdown file found: $file"
+              DOCS_ONLY=false
+              break
+            fi
+          done <<< "$FILES"
+
+          echo "docs_only=${DOCS_ONLY}" >> "$GITHUB_OUTPUT"
+
+      - name: Approve and merge
+        if: steps.check.outputs.docs_only == 'true'
+        env:
+          GITEA_TOKEN: ${{ secrets.GITEA_TOKEN }}
+        run: |
+          PR_NUMBER=${{ github.event.pull_request.number }}
+          API_BASE="${{ github.server_url }}/api/v1/repos/${{ github.repository }}/pulls/${PR_NUMBER}"
+
+          # Approve the PR
+          curl -sf -X POST "${API_BASE}/reviews" \
+            -H "Authorization: token ${GITEA_TOKEN}" \
+            -H "Content-Type: application/json" \
+            -d '{"event": "APPROVED", "body": "Auto-approved: docs-only changes (all .md files)."}'
+
+          # Merge the PR
+          curl -sf -X POST "${API_BASE}/merge" \
+            -H "Authorization: token ${GITEA_TOKEN}" \
+            -H "Content-Type: application/json" \
+            -d '{"Do": "merge", "merge_message_field": "Auto-merge: docs-only PR #'"${PR_NUMBER}"'"}'
+
+          echo "PR #${PR_NUMBER} auto-approved and merged."