feat(platform): add cross-platform editor utilities and refresh functionality

- Add libs/platform/src/editor.ts with cross-platform editor detection and launching
  - Handles Windows .cmd batch scripts (cursor.cmd, code.cmd, etc.)
  - Supports macOS app bundles in /Applications and ~/Applications
  - Includes caching with 5-minute TTL for performance
- Refactor open-in-editor.ts to use @automaker/platform utilities
- Add POST /api/worktree/refresh-editors endpoint to clear cache
- Add refresh button to Settings > Account for IDE selection
- Update useAvailableEditors hook with refresh() and isRefreshing

Fixes Windows issue where "Open in Editor" was falling back to Explorer
because execFile cannot run .cmd scripts without shell:true.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/server/src/routes/worktree/index.ts

@@ -25,6 +25,7 @@ import {
   createOpenInEditorHandler,
   createGetDefaultEditorHandler,
   createGetAvailableEditorsHandler,
+  createRefreshEditorsHandler,
 } from './routes/open-in-editor.js';
 import { createInitGitHandler } from './routes/init-git.js';
 import { createMigrateHandler } from './routes/migrate.js';
@@ -79,6 +80,7 @@ export function createWorktreeRoutes(): Router {
   router.post('/open-in-editor', validatePathParams('worktreePath'), createOpenInEditorHandler());
   router.get('/default-editor', createGetDefaultEditorHandler());
   router.get('/available-editors', createGetAvailableEditorsHandler());
+  router.post('/refresh-editors', createRefreshEditorsHandler());
   router.post('/init-git', validatePathParams('projectPath'), createInitGitHandler());
   router.post('/migrate', createMigrateHandler());
   router.post(