fix: remove duplicate type declarations from client.go and webhook.go

Types ImageID/ContainerID and UnparsedURL are now defined only in their
respective types.go files, fixing the redeclaration compilation error.

internal/service/webhook/webhook.go

@@ -16,12 +16,6 @@ import (
 	"git.eeqj.de/sneak/upaas/internal/service/deploy"
 )
 
-// UnparsedURL is a URL stored as a plain string without parsing.
-// Use this instead of string when the value is known to be a URL
-// but should not be parsed into a net/url.URL (e.g. webhook URLs,
-// compare URLs from external payloads).
-type UnparsedURL string
-
 // ServiceParams contains dependencies for Service.
 type ServiceParams struct {
 	fx.In