Frontend tooling + Linter pass + React rule enforcement (#886)

- Added `oxlint`, `oxfmt`, `vitest`, `knip`
- Configured oxlint rules including react best practices (e.g. for
effect usage)
- Full linting pass on frontend code
- Full react rules pass on effect usage
- Full reformatting using oxfmt
- Full dead code cleanup using knip

.github/workflows/ci.yml

@@ -112,7 +112,7 @@ jobs:
       - name: Set up Node
         uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
         with:
-          node-version: 20
+          node-version: 24
           cache: "npm"
           cache-dependency-path: src/frontend/package-lock.json
 
@@ -120,6 +120,14 @@ jobs:
         working-directory: src/frontend
         run: npm ci
 
+      - name: Lint
+        working-directory: src/frontend
+        run: npm run lint
+
+      - name: Check formatting
+        working-directory: src/frontend
+        run: npm run format:check
+
       - name: Typecheck
         working-directory: src/frontend
         run: npm run typecheck