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/github-issues-view/hooks/use-issue-validation.ts

@@ -1,4 +1,4 @@
-// @ts-nocheck
+// @ts-nocheck - GitHub issue validation with Electron API integration and async state
 import { useState, useEffect, useCallback, useRef } from 'react';
 import { createLogger } from '@automaker/utils/logger';
 import {
@@ -17,17 +17,6 @@ import { useValidateIssue, useMarkValidationViewed } from '@/hooks/mutations';
 
 const logger = createLogger('IssueValidation');
 
-/**
- * Extract model string from PhaseModelEntry or string (handles both formats)
- */
-function extractModel(entry: PhaseModelEntry | string | undefined): ModelId | undefined {
-  if (!entry) return undefined;
-  if (typeof entry === 'string') {
-    return entry as ModelId;
-  }
-  return entry.model;
-}
-
 interface UseIssueValidationOptions {
   selectedIssue: GitHubIssue | null;
   showValidationDialog: boolean;