feat(apply): per-record selection + deletes-before-updates ordering

RecordDiff.Key() gives a stable normalized identifier ("TYPE name.") for
every diff kind, exposed as recordView.Key. ApplyRequest now takes
Updates/Prunes key lists instead of two booleans, so callers can apply a
subset of records. service.Apply builds the applied set with selected
prunes (Delete) added before selected updates (Add/Update) — an
invariant, not an option — since the provider rejects an Add/Update
whose name still conflicts with an existing record (e.g. a CNAME cannot
be created while an A on the same name still exists).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwxdSt4reTm7Dj1oxRvpP3

internal/api/dto.go

@@ -40,11 +40,12 @@ func toAuthResponse(u store.User, p store.Project) authResponse {
 }
 
 type applyRequest struct {
-	ApplyUpdates bool `json:"applyUpdates"`
-	ApplyPrunes  bool `json:"applyPrunes"`
+	Updates []string `json:"updates"`
+	Prunes  []string `json:"prunes"`
 }
 
 type recordView struct {
+	Key      string   `json:"key"`
 	Kind     string   `json:"kind"`
 	Type     string   `json:"type"`
 	Name     string   `json:"name"`
@@ -61,7 +62,7 @@ type changesetResponse struct {
 }
 
 func toRecordView(d diff.RecordDiff) recordView {
-	rv := recordView{Kind: string(d.Kind), Type: string(d.Type), Name: d.Name, ReadOnly: d.ReadOnly}
+	rv := recordView{Key: d.Key(), Kind: string(d.Kind), Type: string(d.Type), Name: d.Name, ReadOnly: d.ReadOnly}
 	if d.Desired != nil {
 		rv.Desired = d.Desired.Values
 	}