fix: close stream adaptive gaps and switch notify to stario v0.1.1

- make stream fast path honor adaptive soft payload limits end-to-end
  - split oversized fast-stream payloads into sequential frames before batching
  - use adaptive soft cap when encoding stream batch payloads
  - move timeout-like error detection into production code for adaptive tx
  - tune notify FrameReader read size explicitly to avoid throughput regression
  - drop local stario replace and depend on released b612.me/stario v0.1.1

stream_batch_codec.go

@@ -0,0 +1,6 @@
+package notify
+
+type streamBatchCodec struct {
+	encodeSingle func(streamFastDataFrame) ([]byte, error)
+	encodeBatch  func([]streamFastDataFrame) ([]byte, error)
+}