docs: add TODO for duplicate JSON parsing optimization

Documents the known performance consideration where bundle data is
parsed twice (Detect + Store). Defers optimization to allow discussion
of implementation approaches.

Signed-off-by: Claude Code <noreply@anthropic.com>
Signed-off-by: Cole Kennedy <cole@testifysec.com>

Author: cole-rgb

pkg/metadatastorage/format/sigstorebundle/handler.go

@@ -34,6 +34,9 @@ func init() {
 }
 
 // Detect returns true if obj is a valid Sigstore bundle
+// TODO(performance): This causes duplicate JSON parsing - IsBundleJSON parses to validate,
+// then Store() parses again. Consider memoization or cheap heuristic detection.
+// See PR discussion for implementation options and trade-offs.
 func (h *Handler) Detect(obj []byte) bool {
 	return sigstorebundle.IsBundleJSON(obj)
 }