Add mock GPS simulator and configurable location sources

miniprogram/engine/sensor/locationSource.ts

@@ -0,0 +1,25 @@
+export type LocationSourceMode = 'real' | 'mock'
+
+export interface LocationSample {
+  latitude: number
+  longitude: number
+  accuracy?: number
+  speed?: number | null
+  headingDeg?: number | null
+  timestamp: number
+  sourceMode: LocationSourceMode
+}
+
+export interface LocationSourceCallbacks {
+  onLocation: (sample: LocationSample) => void
+  onStatus: (message: string) => void
+  onError: (message: string) => void
+}
+
+export interface LocationSource {
+  readonly mode: LocationSourceMode
+  readonly active: boolean
+  start(): void
+  stop(): void
+  destroy(): void
+}