ci: drop redundant npm test step, coverage run covers it

The test:coverage step runs the full suite under Istanbul; running
`npm test` first executes every test twice for no extra signal.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -36,13 +36,7 @@ jobs:
         run: npm run lint
         working-directory: frontend
 
-      - name: Run unit and component tests
+      - name: Run unit and component tests with coverage
-        run: npm test
-        working-directory: frontend
-        env:
-          TZ: Europe/Berlin
-
-      - name: Run coverage (server + client)
         run: npm run test:coverage
         working-directory: frontend
         env: