feat: 添加 2D/3D 地图切换与坐标偏移功能

- 新增 WorldMap 组件，支持 2D 世界地图视图
- 主页添加 2D/3D 视图切换按钮
- 实现确定性坐标偏移算法，分散同城用户位置
- 更新 heatmap 和 register API 使用坐标偏移

lib/geo/offset.ts

@@ -0,0 +1,72 @@
+/**
+ * Generate a deterministic offset based on a unique identifier.
+ * This ensures the same ID always gets the same offset,
+ * allowing multiple users in the same city to be spread out
+ * while maintaining consistent positions.
+ *
+ * @param id - Unique identifier (e.g., claw ID)
+ * @param maxOffsetKm - Maximum offset in kilometers (default: 15km)
+ * @returns Object with lat and lng offsets in degrees
+ */
+export function generateDeterministicOffset(
+  id: string,
+  maxOffsetKm: number = 15
+): { latOffset: number; lngOffset: number } {
+  // Simple hash function to convert string to number
+  let hash = 0;
+  for (let i = 0; i < id.length; i++) {
+    const char = id.charCodeAt(i);
+    hash = ((hash << 5) - hash) + char;
+    hash = hash & hash; // Convert to 32-bit integer
+  }
+
+  // Use the hash to generate two pseudo-random values between -1 and 1
+  // Using simple modulo arithmetic for determinism
+  const seed1 = Math.abs(hash % 10000) / 10000; // 0 to 1
+  const seed2 = Math.abs((hash >> 8) % 10000) / 10000; // 0 to 1
+
+  // Convert to -1 to 1 range with better distribution
+  const factor1 = (seed1 * 2 - 1);
+  const factor2 = (seed2 * 2 - 1);
+
+  // Convert km to degrees (approximate)
+  // 1 degree latitude ≈ 111km
+  // 1 degree longitude varies by latitude (cos(lat) * 111km)
+  // We use a rough average here
+  const kmPerDegree = 111;
+  const maxOffsetDegrees = maxOffsetKm / kmPerDegree;
+
+  return {
+    latOffset: factor1 * maxOffsetDegrees,
+    lngOffset: factor2 * maxOffsetDegrees,
+  };
+}
+
+/**
+ * Apply deterministic offset to coordinates.
+ * This spreads out users in the same city while keeping
+ * each user's position consistent.
+ *
+ * @param lat - Original latitude
+ * @param lng - Original longitude
+ * @param id - Unique identifier for deterministic offset
+ * @param maxOffsetKm - Maximum offset in kilometers
+ * @returns New coordinates with offset applied
+ */
+export function applyDeterministicOffset(
+  lat: number,
+  lng: number,
+  id: string,
+  maxOffsetKm: number = 15
+): { lat: number; lng: number } {
+  const { latOffset, lngOffset } = generateDeterministicOffset(id, maxOffsetKm);
+
+  // Adjust longitude offset based on latitude
+  // (longitude degrees get smaller towards poles)
+  const lngCorrection = Math.cos((lat * Math.PI) / 180);
+
+  return {
+    lat: lat + latOffset,
+    lng: lng + lngOffset * lngCorrection,
+  };
+}