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/main.ts

@@ -28,8 +28,6 @@ import {
   // Electron app bundle operations
   setElectronAppPaths,
   electronAppExists,
-  electronAppReadFileSync,
-  electronAppStatSync,
   electronAppStat,
   electronAppReadFile,
   // System path operations
@@ -108,10 +106,6 @@ async function findAvailablePort(preferredPort: number): Promise<number> {
 // Calculation: 4 columns × 280px + 3 gaps × 20px + 40px padding = 1220px board content
 // With sidebar expanded (288px): 1220 + 288 = 1508px
 // Minimum window dimensions - reduced to allow smaller windows since kanban now supports horizontal scrolling
-const SIDEBAR_EXPANDED = 288;
-const SIDEBAR_COLLAPSED = 64;
-
-const MIN_WIDTH_EXPANDED = 800; // Reduced - horizontal scrolling handles overflow
 const MIN_WIDTH_COLLAPSED = 600; // Reduced - horizontal scrolling handles overflow
 const MIN_HEIGHT = 500; // Reduced to allow more flexibility
 const DEFAULT_WIDTH = 1600;