chore: Fix all lint errors and remove unused code

- Fix 75 ESLint errors by updating eslint.config.mjs:
  - Add missing browser globals (MouseEvent, AbortController, Response, etc.)
  - Add Vite define global (__APP_VERSION__)
  - Configure @ts-nocheck to require descriptions
  - Add no-unused-vars rule for .mjs scripts

- Fix runtime bug in agent-output-modal.tsx (setOutput -> setStreamedContent)

- Remove ~120 unused variable warnings across 97 files:
  - Remove unused imports (React hooks, lucide icons, types)
  - Remove unused constants and variables
  - Remove unused function definitions
  - Prefix intentionally unused parameters with underscore

- Add descriptions to all @ts-nocheck comments (25 files)

- Clean up misc issues:
  - Remove invalid deprecation plugin comments
  - Fix eslint-disable comment placement
  - Add missing RefreshCw import in code-view.tsx

Reduces lint warnings from ~300 to 67 (all remaining are no-explicit-any)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/ui/tests/features/feature-manual-review-flow.spec.ts

@@ -62,19 +62,6 @@ test.describe('Feature Manual Review Flow', () => {
     const featureDir = path.join(automakerDir, 'features', featureId);
     fs.mkdirSync(featureDir, { recursive: true });
 
-    const feature = {
-      id: featureId,
-      description: 'Test feature for manual review flow',
-      category: 'test',
-      status: 'waiting_approval',
-      skipTests: true,
-      model: 'sonnet',
-      thinkingLevel: 'none',
-      createdAt: new Date().toISOString(),
-      branchName: '',
-      priority: 2,
-    };
-
     // Note: Feature is created via HTTP API in the test itself, not in beforeAll
     // This ensures the feature exists when the board view loads it
   });