Moved the weatherfeeder model out of internal/ so that downstream consumers can import it directly.

model/doc.go

@@ -0,0 +1,10 @@
+// FILE: internal/model/doc.go
+// Package model defines weatherfeeder's canonical domain payload types.
+//
+// These structs are emitted as the Payload of canonical events (schemas "weather.*.vN").
+// JSON tags are treated as part of the wire contract for sinks (stdout today; others later).
+//
+// Compatibility guidance:
+//   - Prefer additive changes.
+//   - Avoid renaming/removing fields without a schema version bump.
+package model