ci: add tests workflow + gate releases on tests passing

- .gitea/workflows/tests.yml: run `unittest discover` on push + pull_request.
  `core` job (stdlib install, GUI tests skip) is bulletproof; `gui-smoke` job
  installs the GUI extra + offscreen Qt libs and runs the suite headless.
- release.yml: add a `test` job and `release: needs: test` so a push to main
  can't publish if the tests fail.

No version bump — CI config only; nothing in the shipped app changed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -11,7 +11,20 @@ on:
     branches: [main]
 
 jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - name: Install (core only)
+        run: python -m pip install -e .
+      - name: Run tests
+        run: python -m unittest discover -s tests -v
+
   release:
+    needs: test          # don't publish a release if the tests fail
     runs-on: ubuntu-latest
     steps:
       - name: Checkout

.gitea/workflows/tests.yml

@@ -0,0 +1,43 @@
+name: tests
+run-name: Run test suite
+
+# Runs the unittest suite on every push and pull request. Two jobs:
+#   core      — stdlib-only install; the GUI tests skip (@skipUnless HAVE_QT). Bulletproof.
+#   gui-smoke — installs the GUI extra + offscreen Qt libs and runs the same suite headless,
+#               exercising the MainWindow/SetupWizard/DiagnosticDialog construction tests.
+# Make `core` a required status check on `main` so a PR can't merge with failing tests.
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  core:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - name: Install (core only — no PySide6)
+        run: python -m pip install -e .
+      - name: Run tests (GUI tests skip without PySide6)
+        run: python -m unittest discover -s tests -v
+
+  gui-smoke:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+      - name: System libraries for offscreen Qt
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libegl1 libgl1 libxkbcommon0 libdbus-1-3 libglib2.0-0
+      - name: Install (with GUI extra)
+        run: python -m pip install -e ".[gui]"
+      - name: Run tests (headless)
+        env:
+          QT_QPA_PLATFORM: offscreen
+        run: python -m unittest discover -s tests -v