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/lib/electron.ts

@@ -1037,7 +1037,8 @@ if (typeof window !== 'undefined') {
 }
 
 // Mock API for development/fallback when no backend is available
-const getMockElectronAPI = (): ElectronAPI => {
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+const _getMockElectronAPI = (): ElectronAPI => {
   return {
     ping: async () => 'pong (mock)',
 
@@ -1456,7 +1457,7 @@ function createMockSetupAPI(): SetupAPI {
       };
     },
 
-    storeApiKey: async (provider: string, apiKey: string) => {
+    storeApiKey: async (provider: string, _apiKey: string) => {
       console.log('[Mock] Storing API key for:', provider);
       // In mock mode, we just pretend to store it (it's already in the app store)
       return { success: true };
@@ -1511,12 +1512,12 @@ function createMockSetupAPI(): SetupAPI {
       };
     },
 
-    onInstallProgress: (callback) => {
+    onInstallProgress: (_callback) => {
       // Mock progress events
       return () => {};
     },
 
-    onAuthProgress: (callback) => {
+    onAuthProgress: (_callback) => {
       // Mock auth events
       return () => {};
     },
@@ -1955,7 +1956,7 @@ function createMockWorktreeAPI(): WorktreeAPI {
       };
     },
 
-    onDevServerLogEvent: (callback) => {
+    onDevServerLogEvent: (_callback) => {
       console.log('[Mock] Subscribing to dev server log events');
       // Return unsubscribe function
       return () => {
@@ -2007,7 +2008,7 @@ function createMockWorktreeAPI(): WorktreeAPI {
       };
     },
 
-    onInitScriptEvent: (callback) => {
+    onInitScriptEvent: (_callback) => {
       console.log('[Mock] Subscribing to init script events');
       // Return unsubscribe function
       return () => {
@@ -2067,7 +2068,7 @@ function createMockWorktreeAPI(): WorktreeAPI {
       };
     },
 
-    onTestRunnerEvent: (callback) => {
+    onTestRunnerEvent: (_callback) => {
       console.log('[Mock] Subscribing to test runner events');
       // Return unsubscribe function
       return () => {
@@ -2212,7 +2213,7 @@ function createMockAutoModeAPI(): AutoModeAPI {
       return { success: true, passes: true };
     },
 
-    resumeFeature: async (projectPath: string, featureId: string, useWorktrees?: boolean) => {
+    resumeFeature: async (projectPath: string, featureId: string, _useWorktrees?: boolean) => {
       if (mockRunningFeatures.has(featureId)) {
         return {
           success: false,
@@ -2348,7 +2349,7 @@ function createMockAutoModeAPI(): AutoModeAPI {
       featureId: string,
       prompt: string,
       imagePaths?: string[],
-      useWorktrees?: boolean
+      _useWorktrees?: boolean
     ) => {
       if (mockRunningFeatures.has(featureId)) {
         return {
@@ -2703,7 +2704,7 @@ function emitSpecRegenerationEvent(event: SpecRegenerationEvent) {
 async function simulateSpecCreation(
   projectPath: string,
   projectOverview: string,
-  generateFeatures = true
+  _generateFeatures = true
 ) {
   mockSpecRegenerationPhase = 'initialization';
   emitSpecRegenerationEvent({