fix(server): handle router setup panic and return error

* return error from New function if route registration panics
* add googleDispatch to handle model:action routing

pkg/server/trace.go

@@ -7,7 +7,10 @@ import (
 
 type contextKey int
 
-const traceKey contextKey = iota
+const (
+	traceKey contextKey = iota
+	modelKey
+)
 
 // RequestTrace holds per-request timing data populated by handlers and middleware.
 type RequestTrace struct {