CI: add tsc --noEmit TypeScript type checking to test job

Adds a step to install Node.js and run tsc --noEmit in the frontend
directory, catching TypeScript type errors before images are built.
Ruff was already present; this completes issue #260.

Closes leeworks-agents/SPARC#260

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build.yaml

@@ -33,6 +33,14 @@ jobs:
         run: |
           ruff check SPARC/ tests/
 
+      - name: Install Node.js and check TypeScript types
+        shell: sh
+        run: |
+          apk add --no-cache nodejs npm
+          cd frontend
+          npm ci
+          npx tsc --noEmit
+
       - name: Run pytest
         shell: sh
         env: