Moved common HTTP body fetch code into a shared helper function.

internal/normalizers/common/payload.go

@@ -1,4 +1,3 @@
-// FILE: ./internal/normalizers/common/payload.go
 package common
 
 import (
@@ -8,7 +7,7 @@ import (
 	"gitea.maximumdirect.net/ejr/feedkit/event"
 )
 
-// PayloadBytes extracts a JSON-ish payload into bytes suitable for json.Unmarshal.
+// PayloadBytes extracts a JSON payload into bytes suitable for json.Unmarshal.
 //
 // Supported payload shapes (weatherfeeder convention):
 //   - json.RawMessage  (recommended for raw events)