chore(ci): add auto-complete TODO workflow

Introduce Gitea Actions workflow to automatically move TODO files from queued to completed on PR events for feature branches.
Update README with setup instructions and benefits.

.gitea/workflows/auto-complete-todo.yml

@@ -0,0 +1,37 @@
+name: 'Auto-complete TODO'
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  move-todo:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Clone PR branch, move TODO, push update'
+        env:
+          PAT_TOKEN: ${{ secrets.PAT_TOKEN }}
+          SERVER_URL: ${{ github.server_url }}
+          REPO_OWNER: ${{ github.repository_owner }}
+          REPO_NAME: ${{ github.event.pull_request.head.repo.name }}
+          PR_BRANCH: ${{ github.head_ref }}
+        run: |
+          git clone https://${PAT_TOKEN}@${SERVER_URL}/${REPO_OWNER}/${REPO_NAME}.git pr-temp || exit 1
+          cd pr-temp
+          git checkout ${PR_BRANCH}
+          BRANCH=$(git rev-parse --abbrev-ref HEAD)
+          TODO_NAME="${BRANCH#feature/}.md"
+          if [[ "${BRANCH}" == feature/* && -f todo/queued/${TODO_NAME} ]]; then
+            mkdir -p todo/completed
+            mv todo/queued/${TODO_NAME} todo/completed/
+            git config user.name 'Gitea Actions Bot'
+            git config user.email 'actions@noreply.local'
+            git add todo/
+            git commit -m "chore: auto-complete ${TODO_NAME} via Gitea Actions"
+            git push https://${PAT_TOKEN}@${SERVER_URL}/${REPO_OWNER}/${REPO_NAME}.git ${PR_BRANCH}
+            echo "✅ Moved todo/queued/${TODO_NAME} → completed/"
+          else
+            echo "ℹ️ No action: branch='${BRANCH}', expected 'feature/*' with todo/queued/${TODO_NAME}"
+          fi
+          cd ..
+          rm -rf pr-temp

README.md

@@ -481,6 +481,18 @@ git commit -m "chore: complete some-todo"
 git push origin master
 ```
 
+### Gitea Actions Automation *(automates post-merge above)*
+
+[`.gitea/workflows/auto-complete-todo.yml`](.gitea/workflows/auto-complete-todo.yml) triggers on PR `opened`/`synchronize`:
+
+- Branches `feature/some-todo`: moves `todo/queued/some-todo.md` → `completed/`.
+
+**One-time setup** (Gitea → Repo → Settings → Secrets & Variables → Actions):
+- New Secret: `PAT_TOKEN` = [Personal Access Token](https://gitea.example.com/user/settings/tokens) (scope: `repo`).
+- Optional: Branch protection → Require "Auto-complete TODO" status check.
+
+**Result**: No manual post-merge steps needed!
+
 ## Documentation
 
 - 📖 [Troubleshooting Guide](docs/TROUBLESHOOTING.md) - Common issues and solutions