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

model/wmo.go

@@ -0,0 +1,15 @@
+package model
+
+// WMOCode is the canonical internal “current conditions” vocabulary.
+//
+// We standardize on the WMO weather interpretation codes used by providers like
+// Open-Meteo, and we map other providers (e.g., NWS) into these codes.
+//
+// Reference codes include: 0,1,2,3,45,48,51,53,...,99.
+type WMOCode int
+
+const (
+	// WMOUnknown is used when we cannot confidently map an upstream condition
+	// into a known WMO code.
+	WMOUnknown WMOCode = -1
+)