v1.4.0: generic Stream[T] — typed stream messages, drop (T, *Stream, error)

- Stream[T]: Send(v T) type-safe; message type recovered from the
  instantiated Send signature (reflect has no type-args API)
- method signatures reduced to (error), (T, error), (*Stream[T], error);
  the (T, *Stream, error) first-message form is gone — send it via Send
- return T and stream message T now run checkType at bind time
  (Stream[any] remains the explicit untyped escape hatch)
- generated clients: TS onMessage: (data: T); Go <-chan T
- fix vacuous panic assertions (fmt.Sprint(nil) -> "<nil>") in
  hardening/route test catch helpers

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

gen_reliability_test.go

@@ -25,12 +25,12 @@ func (*AlphaGenSvc) Ping() error                                { return nil }
 
 type MixedGenSvc struct{}
 
-func (*MixedGenSvc) Request() (string, error) { return "", nil }
-func (*MixedGenSvc) Stream() (*Stream, error) { return &Stream{}, nil }
+func (*MixedGenSvc) Request() (string, error)      { return "", nil }
+func (*MixedGenSvc) Stream() (*Stream[any], error) { return &Stream[any]{}, nil }
 
 type ZebraGenSvc struct{}
 
-func (*ZebraGenSvc) Watch() (*Stream, error) { return &Stream{}, nil }
+func (*ZebraGenSvc) Watch() (*Stream[any], error) { return &Stream[any]{}, nil }
 
 type GenOnlyDependency struct{}