add Makefile test-layer targets + rename coverage.sh

Makefile grows targets for each test layer (test, test-a11y,
test-integration, test-e2e, test-all), the coverage + smoke-bundle
helpers, and the UI harness (ui-dev, ui-stop, ui-smoke). push-check
now runs `test + test-a11y` — fast pre-push gate under 90s.

ci/coverage.sh is renamed to ci/test_coverage.sh so it matches the
`test_*.sh` naming of the other layer scripts and sidesteps the
repo's `coverage.*` gitignore pattern (intended for coverage output
files like coverage.lcov, not scripts).

Co-Authored-By: Claude <noreply@anthropic.com>

.gitea/workflows/test.yml

@@ -26,7 +26,7 @@ jobs:
       - run: (cd app && flutter pub get)
       - run: ci/test.sh
       - run: ci/test_a11y.sh
-      - run: ci/coverage.sh
+      - run: ci/test_coverage.sh
 
   integration:
     name: integration_test (xvfb)