ci: enforce lint in CI (fail build on lint errors)

Remove continue-on-error from lint step so lint errors will now
fail the Tests workflow and turn the badge red.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: dannyshmueli

.github/workflows/tests.yml

@@ -39,7 +39,6 @@ jobs:
 
       - name: Run linting
         run: npm run lint
-        continue-on-error: true
 
       - name: Run type checking
         run: npm run type-check