docs: describe project structure

src/domain/photo.ts

@@ -0,0 +1,9 @@
+export interface Photo {
+  id: string;
+  fileName: string;
+  capturedAt: string | null;
+  latitude: number | null;
+  longitude: number | null;
+  thumbnailUrl: string | null;
+}
+

src/domain/route.ts

@@ -0,0 +1,7 @@
+export interface RoutePoint {
+  photoId: string;
+  capturedAt: string;
+  latitude: number;
+  longitude: number;
+}
+