Add Geofence frontend UI with management and event history

Implemented complete frontend for the Geofence MVP feature:

**Pages:**
- /admin/geofences - Management page with create/edit/delete modals
- /admin/geofences/events - Event history with stats and filters
- Dashboard widget showing active geofences and recent events

**Features:**
- Create/Edit geofences with device selection, coordinates, radius, and color
- Toggle active/inactive status
- View enter/exit events with notification status
- Auto-refresh every 30 seconds
- Zone limit enforcement (5 for users, unlimited for admins)
- Stats cards showing total events, enters, exits, and notifications

**API:**
- GET /api/geofences/events - Fetch events with optional filters

All frontend components follow the existing admin panel design system
with gradient backgrounds, shadow effects, and responsive layouts.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/api/geofences/events/route.ts

@@ -0,0 +1,69 @@
+import { NextResponse } from "next/server";
+import { auth } from "@/lib/auth";
+import { geofenceDb } from "@/lib/geofence-db";
+
+// GET /api/geofences/events - List all geofence events for the authenticated user
+export async function GET(request: Request) {
+  try {
+    const session = await auth();
+
+    if (!session?.user) {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
+
+    const userId = (session.user as any).id;
+
+    // Get all geofences owned by this user
+    const userGeofences = geofenceDb.findByOwner(userId);
+    const geofenceIds = userGeofences.map((g) => g.id);
+
+    if (geofenceIds.length === 0) {
+      return NextResponse.json({
+        success: true,
+        events: [],
+        total: 0,
+      });
+    }
+
+    // Parse query parameters
+    const { searchParams } = new URL(request.url);
+    const deviceId = searchParams.get("deviceId") || undefined;
+    const geofenceId = searchParams.get("geofenceId") || undefined;
+    const limit = parseInt(searchParams.get("limit") || "100");
+
+    // Get events (filtered by user's geofences)
+    let events = geofenceDb.findEvents({
+      deviceId,
+      geofenceId,
+      limit,
+    });
+
+    // Filter to only events from user's geofences
+    events = events.filter((event) => geofenceIds.includes(event.geofence_id));
+
+    // Enrich events with geofence and device names
+    const enrichedEvents = events.map((event) => {
+      const geofence = userGeofences.find((g) => g.id === event.geofence_id);
+      return {
+        ...event,
+        geofenceName: geofence?.name || "Unknown",
+        geofenceColor: geofence?.color || "#gray",
+      };
+    });
+
+    return NextResponse.json({
+      success: true,
+      events: enrichedEvents,
+      total: enrichedEvents.length,
+    });
+  } catch (error) {
+    console.error("[GET /api/geofences/events] Error:", error);
+    return NextResponse.json(
+      {
+        error: "Failed to fetch geofence events",
+        details: error instanceof Error ? error.message : "Unknown error",
+      },
+      { status: 500 }
+    );
+  }
+}