feat: check formatting, linting and tests in CI

Every push runs ruff, prettier, pytest and svelte-check; a tagged release runs the
blocking half again before it publishes an image. eslint and svelte-check report
without failing, since 87 and 30 findings predate the workflow.

.gitea/workflows/release.yml

@@ -23,7 +23,42 @@ env:
   REGISTRY: git.jaroszew.ski
 
 jobs:
+  # The blocking half of ci.yml, run again on the tagged commit so a release cannot publish
+  # an image whose tests fail. Deliberately duplicated rather than shared: Gitea's support
+  # for reusable workflows is thinner than GitHub's, and this is a dozen lines.
+  # Keep in step with ci.yml.
+  quality:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install uv
+        run: |
+          curl -LsSf https://astral.sh/uv/install.sh | sh
+          echo "$HOME/.local/bin" >> "$GITHUB_PATH"
+
+      - name: Backend format, lint and tests
+        working-directory: backend
+        run: |
+          uv sync --locked
+          uv run ruff format --check src/
+          uv run ruff check src/
+          uv run pytest tests/ -q
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 24
+
+      - name: Frontend format
+        working-directory: frontend
+        run: |
+          corepack enable
+          pnpm install --frozen-lockfile
+          pnpm exec prettier --check .
+
   build:
+    needs: quality
     runs-on: ubuntu-latest
 
     strategy: