ci: port workflows from .github/ to .forgejo/ (Forgejo Actions)

GitHub torrentclaw org is shadow-banned; CI is hosted at git.torrentclaw.com
now. Move workflows into the runner's natively-watched .forgejo/workflows/
tree and adapt steps to run in the available 'docker'-labeled Forgejo runner
without GitHub-only tooling (gh CLI, third-party marketplace actions).

- Use container: image to ship the toolchain (no actions/setup-* needed).
- Drop GitHub-only marketplace actions in favour of upstream installers
  invoked over curl/apt.
- Where a workflow created a GitHub Release (release.yml), substitute the
  step with a curl call against the Forgejo Releases API
  (POST /repos/<owner>/<repo>/releases).

.github/workflows/ci.yml

@@ -1,55 +0,0 @@
-name: CI
-
-on:
-  pull_request:
-    branches: [main]
-  push:
-    branches: [main]
-
-permissions:
-  contents: read
-
-jobs:
-  lint-commits:
-    name: Lint commits
-    runs-on: ubuntu-latest
-    if: github.event_name == 'pull_request'
-    steps:
-      - uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-
-      - uses: actions/setup-node@v4
-        with:
-          node-version: "22"
-
-      - name: Install dependencies
-        run: npm ci
-
-      - name: Validate conventional commits
-        run: npx commitlint --from ${{ github.event.pull_request.base.sha }} --to ${{ github.event.pull_request.head.sha }} --verbose
-
-  build-and-test:
-    name: Build & test
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - uses: actions/setup-node@v4
-        with:
-          node-version: "22"
-
-      - name: Install dependencies
-        run: npm ci
-
-      - name: Check formatting
-        run: npx prettier --check .
-
-      - name: Typecheck
-        run: npx tsc --noEmit
-
-      - name: Build
-        run: npm run build
-
-      - name: Test
-        run: npm test