internal/rosa: remove unused helpers

These are no longer needed after migration.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/state.go

@@ -411,7 +411,7 @@ func (s *S) Collect() (handles P) {
 type deferredGit struct {
 	url      string
 	tag      string
-	checksum string
+	checksum pkg.Checksum
 }
 
 // getFrame must be called before accessing s.
@@ -661,13 +661,15 @@ func (s *S) getFrame() azalea.Frame {
 				args azalea.FArgs,
 			) (v any, set bool, err error) {
 				var a deferredGit
+				var checksum string
 				if err = args.Apply(map[unique.Handle[azalea.Ident]]any{
 					k("url"):      &a.url,
 					k("tag"):      &a.tag,
-					k("checksum"): &a.checksum,
+					k("checksum"): &checksum,
 				}); err != nil {
 					return
 				}
+				a.checksum = mustDecode(checksum)
 				v = a
 				set = true
 				return
@@ -1047,7 +1049,7 @@ func (ctx *evalContext) pf(
 		source = p
 
 	case deferredGit:
-		source = ctx.t.newTagRemote(p.url, p.tag, p.checksum)
+		source = ctx.t.NewViaGit(p.url, "refs/tags/"+p.tag, p.checksum)
 
 	case azalea.Ident:
 		var _meta *Metadata