Add bun integration tests for docs flow, update integration guide

- Add test/integration.test.ts: getServicePublicKey, full flow (register, login, createCollection, createPointFeature, listFeatures)
- Update docs example: registerBySigningServiceKey then loginWithSignature
- Document integration tests in typescript-frontend-integration.md

Made-with: Cursor

cmd/api/main.go

@@ -27,8 +27,22 @@ func main() {
 		servicePublicKey = adminPublicKey
 	}
 
-	memory := store.NewMemoryStore()
-	service := app.NewService(memory, app.Config{
+	var st store.Store
+	if databaseURL := os.Getenv("DATABASE_URL"); databaseURL != "" {
+		if err := store.Migrate(databaseURL); err != nil {
+			log.Fatalf("migrate: %v", err)
+		}
+		pg, err := store.NewPostgresStore(databaseURL)
+		if err != nil {
+			log.Fatalf("postgres: %v", err)
+		}
+		defer pg.Close()
+		st = pg
+	} else {
+		st = store.NewMemoryStore()
+	}
+
+	service := app.NewService(st, app.Config{
 		ChallengeTTL: 5 * time.Minute,
 		SessionTTL:   24 * time.Hour,
 	}, servicePublicKey)