Remove incorrect 'internal/' prefix from model package file header comments

model/alert.go

@@ -1,4 +1,4 @@
-// FILE: internal/model/alert.go
+// FILE: model/alert.go
 package model
 
 import "time"

model/doc.go

@@ -1,4 +1,4 @@
-// FILE: internal/model/doc.go
+// FILE: 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").

model/forecast.go

@@ -1,4 +1,4 @@
-// FILE: internal/model/forecast.go
+// FILE: model/forecast.go
 package model
 
 import "time"

model/observation.go

@@ -1,4 +1,4 @@
-// FILE: internal/model/observation.go
+// FILE: model/observation.go
 package model
 
 import "time"