fix(ci): use list-form mypy_path and switch frontend job to npm install

.github/workflows/ci.yml

@@ -115,7 +115,7 @@ jobs:
           cache-dependency-path: frontend/package-lock.json
 
       - name: Install dependencies
-        run: npm ci
+        run: npm install --no-audit --no-fund
 
       - name: Lint
         run: npm run lint

pyproject.toml

@@ -193,8 +193,9 @@ warn_unused_ignores = true
 warn_no_return = true
 no_implicit_optional = true
 files = ["src/captioning", "backend/app", "scripts"]
-mypy_path = "src:backend"
+mypy_path = ["src", "backend"]
 explicit_package_bases = true
+namespace_packages = true
 
 [[tool.mypy.overrides]]
 module = [