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/src/components/views/graph-view-page.tsx

@@ -1,4 +1,4 @@
-// @ts-nocheck
+// @ts-nocheck - graph view page with feature filtering and visualization state
 import { useState, useCallback, useMemo, useEffect } from 'react';
 import { useAppStore, Feature } from '@/store/app-store';
 import { useShallow } from 'zustand/react/shallow';
@@ -9,12 +9,7 @@ import {
   AgentOutputModal,
   BacklogPlanDialog,
 } from './board-view/dialogs';
-import {
-  useBoardFeatures,
-  useBoardActions,
-  useBoardBackground,
-  useBoardPersistence,
-} from './board-view/hooks';
+import { useBoardFeatures, useBoardActions, useBoardPersistence } from './board-view/hooks';
 import { useWorktrees } from './board-view/worktree-panel/hooks';
 import { useAutoMode } from '@/hooks/use-auto-mode';
 import { pathsEqual } from '@/lib/utils';
@@ -242,7 +237,7 @@ export function GraphViewPage() {
   const [followUpFeature, setFollowUpFeature] = useState<Feature | null>(null);
   const [followUpPrompt, setFollowUpPrompt] = useState('');
   const [followUpImagePaths, setFollowUpImagePaths] = useState<any[]>([]);
-  const [followUpPreviewMap, setFollowUpPreviewMap] = useState<Map<string, string>>(new Map());
+  const [, setFollowUpPreviewMap] = useState<Map<string, string>>(new Map());
 
   // In-progress features for shortcuts
   const inProgressFeaturesForShortcuts = useMemo(() => {