refactor: extract models/routes and env-based server config

- Move API request/response structs into new lib/models package
- Centralize Gin route registration in lib/routing to simplify wiring
- Add lib/server config helper to allow WARPBOX_BOX_POLL_INTERVAL_MS override
- Improves modularity and makes polling behavior configurable per environmentrefactor: extract models/routes and env-based server config

- Move API request/response structs into new lib/models package
- Centralize Gin route registration in lib/routing to simplify wiring
- Add lib/server config helper to allow WARPBOX_BOX_POLL_INTERVAL_MS override
- Improves modularity and makes polling behavior configurable per environment

lib/routing/routes.go

@@ -0,0 +1,33 @@
+package routing
+
+import "github.com/gin-gonic/gin"
+
+type Handlers struct {
+	Index              gin.HandlerFunc
+	ShowBox            gin.HandlerFunc
+	BoxStatus          gin.HandlerFunc
+	DownloadBox        gin.HandlerFunc
+	DownloadFile       gin.HandlerFunc
+	CreateBox          gin.HandlerFunc
+	ManifestFileUpload gin.HandlerFunc
+	FileStatusUpdate   gin.HandlerFunc
+	DirectBoxUpload    gin.HandlerFunc
+	LegacyUpload       gin.HandlerFunc
+}
+
+func Register(router *gin.Engine, handlers Handlers) {
+	router.GET("/", handlers.Index)
+
+	router.GET("/box/:id", handlers.ShowBox)
+	router.GET("/box/:id/status", handlers.BoxStatus)
+	router.GET("/box/:id/download", handlers.DownloadBox)
+	router.GET("/box/:id/files/:filename", handlers.DownloadFile)
+
+	router.POST("/box", handlers.CreateBox)
+	router.POST("/box/:id/files/:file_id/upload", handlers.ManifestFileUpload)
+	router.POST("/box/:id/files/:file_id/status", handlers.FileStatusUpdate)
+
+	// Legacy upload routes are kept for compatibility with older clients.
+	router.POST("/box/:id/upload", handlers.DirectBoxUpload)
+	router.POST("/upload", handlers.LegacyUpload)
+}