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/hooks/use-electron-agent.ts

@@ -1,4 +1,4 @@
-// @ts-nocheck
+// @ts-nocheck - Electron IPC boundary typing with stream events and message queuing
 import { useState, useEffect, useCallback, useRef } from 'react';
 import type { Message, StreamEvent } from '@/types/electron';
 import { useMessageQueue } from './use-message-queue';
@@ -161,16 +161,15 @@ export function useElectronAgent({
   );
 
   // Message queue for queuing messages when agent is busy
-  const { queuedMessages, isProcessingQueue, addToQueue, clearQueue, processNext } =
-    useMessageQueue({
-      onProcessNext: async (queuedMessage) => {
-        await sendMessageDirectly(
-          queuedMessage.content,
-          queuedMessage.images,
-          queuedMessage.textFiles
-        );
-      },
-    });
+  const { queuedMessages, isProcessingQueue, clearQueue, processNext } = useMessageQueue({
+    onProcessNext: async (queuedMessage) => {
+      await sendMessageDirectly(
+        queuedMessage.content,
+        queuedMessage.images,
+        queuedMessage.textFiles
+      );
+    },
+  });
 
   // Initialize connection and load history
   useEffect(() => {