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/electron.ts

@@ -482,6 +482,9 @@ export interface ElectronAPI {
       sessionId: string
     ) => Promise<{ success: boolean; error?: string }>;
   };
+  claude?: {
+    getUsage: () => Promise<any>;
+  };
 }
 
 // Note: Window interface is declared in @/types/electron.d.ts
@@ -879,6 +882,33 @@ const getMockElectronAPI = (): ElectronAPI => {
 
     // Mock Running Agents API
     runningAgents: createMockRunningAgentsAPI(),
+
+    // Mock Claude API
+    claude: {
+      getUsage: async () => {
+        console.log("[Mock] Getting Claude usage");
+        return {
+          sessionTokensUsed: 0,
+          sessionLimit: 0,
+          sessionPercentage: 15,
+          sessionResetTime: new Date(Date.now() + 3600000).toISOString(),
+          sessionResetText: "Resets in 1h",
+          weeklyTokensUsed: 0,
+          weeklyLimit: 0,
+          weeklyPercentage: 5,
+          weeklyResetTime: new Date(Date.now() + 86400000 * 2).toISOString(),
+          weeklyResetText: "Resets Dec 23",
+          opusWeeklyTokensUsed: 0,
+          opusWeeklyPercentage: 1,
+          opusResetText: "Resets Dec 27",
+          costUsed: null,
+          costLimit: null,
+          costCurrency: null,
+          lastUpdated: new Date().toISOString(),
+          userTimezone: "UTC"
+        };
+      },
+    }
   };
 };