feat: integrate real data into dashboard

- Created dashboard service with DB queries for users, economy, events
- Added client stats provider with 30s caching for Discord metrics
- Implemented /api/stats endpoint aggregating all dashboard data
- Created useDashboardStats React hook with auto-refresh
- Updated Dashboard.tsx to display real data with loading/error states
- Added comprehensive test coverage (11 tests passing)
- Replaced all mock values with live Discord and database metrics

bot/lib/clientStats.test.ts

@@ -0,0 +1,74 @@
+import { describe, test, expect, beforeEach, mock, afterEach } from "bun:test";
+import { getClientStats, clearStatsCache } from "./clientStats";
+
+// Mock AuroraClient
+mock.module("./BotClient", () => ({
+    AuroraClient: {
+        guilds: {
+            cache: {
+                size: 5,
+            },
+        },
+        ws: {
+            ping: 42,
+        },
+        users: {
+            cache: {
+                size: 100,
+            },
+        },
+        commands: {
+            size: 20,
+        },
+        lastCommandTimestamp: 1641481200000,
+    },
+}));
+
+describe("clientStats", () => {
+    beforeEach(() => {
+        clearStatsCache();
+    });
+
+    test("should return client stats", () => {
+        const stats = getClientStats();
+
+        expect(stats.guilds).toBe(5);
+        expect(stats.ping).toBe(42);
+        expect(stats.cachedUsers).toBe(100);
+        expect(stats.commandsRegistered).toBe(20);
+        expect(typeof stats.uptime).toBe("number"); // Can't mock process.uptime easily
+        expect(stats.lastCommandTimestamp).toBe(1641481200000);
+    });
+
+    test("should cache stats for 30 seconds", () => {
+        const stats1 = getClientStats();
+        const stats2 = getClientStats();
+
+        // Should return same object (cached)
+        expect(stats1).toBe(stats2);
+    });
+
+    test("should refresh cache after TTL expires", async () => {
+        const stats1 = getClientStats();
+
+        // Wait for cache to expire (simulate by clearing and waiting)
+        await new Promise(resolve => setTimeout(resolve, 35));
+        clearStatsCache();
+
+        const stats2 = getClientStats();
+
+        // Should be different objects (new fetch)
+        expect(stats1).not.toBe(stats2);
+        // But values should be the same (mocked client)
+        expect(stats1.guilds).toBe(stats2.guilds);
+    });
+
+    test("clearStatsCache should invalidate cache", () => {
+        const stats1 = getClientStats();
+        clearStatsCache();
+        const stats2 = getClientStats();
+
+        // Should be different objects
+        expect(stats1).not.toBe(stats2);
+    });
+});