ci: enforce mypy type checking (all errors fixed)

.gitea/workflows/ci.yml

@@ -41,14 +41,8 @@ jobs:
       - name: Ruff format
         run: ruff format --check app/ tests/ fpaste
 
-      - name: Type check (informational)
-        run: |
-          errors=$(mypy app/ --ignore-missing-imports 2>&1 | grep -c "error:" || true)
-          echo "mypy found $errors type errors"
-          if [ "$errors" -gt 20 ]; then
-            echo "::warning::mypy errors increased to $errors (baseline: 20)"
-          fi
-        continue-on-error: true
+      - name: Type check
+        run: mypy app/ tests/ fpaste --ignore-missing-imports
 
   security:
     name: Security Scan