Unify product version at 1.4.0, add ruff gate, drop stale GitHub workflow

- One version (1.4.0) across extension/manifest.json, automation/pyproject.toml,
  automation-js/package.json (+lockfile); README documents the bump-together policy
- Delete .github/workflows/ci.yml (behind the Gitea copy; CI runs on Gitea Actions)
- CURSOR_PROMPT.md: replace personal paths with <path-to-context-extractor>
- Add ruff (E4,E7,E9,F,I, line-length 120) to automation/ dev extras, Makefile lint,
  and the Gitea CI Lint + tests job as a hard gate

.gitea/workflows/ci.yml

@@ -66,6 +66,9 @@ jobs:
           python -m pip install --upgrade pip
           pip install -e ".[dev]"
 
+      - name: Ruff lint
+        run: ruff check .
+
       - name: Install Playwright Chromium
         run: playwright install --with-deps chromium