feat: add Claude usage tracking via CLI

Adds a Claude usage tracking feature that displays session, weekly, and Sonnet usage stats. Uses the Claude CLI's /usage command to fetch data (no API key required).

Features:
- Usage popover in board header showing session, weekly, and Sonnet limits
- Progress bars with color-coded status (green/orange/red)
- Auto-refresh with configurable interval
- Caching of usage data with stale indicator
- Settings section for refresh interval configuration

Server:
- ClaudeUsageService: Executes Claude CLI via PTY (expect) to fetch usage
- New /api/claude/usage endpoint

UI:
- ClaudeUsagePopover component with usage cards
- ClaudeUsageSection in settings for configuration
- Integration with app store for persistence

apps/ui/src/lib/http-api-client.ts

@@ -1016,6 +1016,11 @@ export class HttpApiClient implements ElectronAPI {
     ): Promise<{ success: boolean; error?: string }> =>
       this.httpDelete(`/api/sessions/${sessionId}`),
   };
+
+  // Claude API
+  claude = {
+    getUsage: (): Promise<any> => this.get("/api/claude/usage"),
+  };
 }
 
 // Singleton instance