feat(topdata): parts autogen from CDN part.yml channel

Phase 2 of the parts-row autogen design: Crucible resolves parts 2DA rows
from the immutable part.yml published with the asset HAK release, over the
anonymous Bunny CDN channel, with the parts consumer required (no fail-open).

- generalize resolveCDNChannelManifest: derive manifest basename + provenance
  label from config; drop hardcoded assets/vfxs.yml so part.yml resolves too
- add filterPartsCDNChannelEntries + mode dispatch implementing the inventory
  contract (restype mdl under part/<cat>/, trailing-digit row id, dedup
  l/r/race/gender variants, sort by source, zero accepted rows = hard fail)
- support hand category + parts/hand dataset mapping (12 datasets total)
- native pipeline: single augment -> normalize -> override sequence with the
  configured parts_rows policy; overrides may update but never synthesize a row
- reject multiple parts_rows consumers in project validation
- tests: parts filter contract, category coverage, offline basename, orphan
  override reject, and a parity guard proving a bare CDN-only parts build

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/project/project_test.go

@@ -1864,6 +1864,20 @@ func TestValidateAutogenConsumerSourcesCDNChannel(t *testing.T) {
 	}
 }
 
+func TestValidateRejectsMultiplePartsRowsConsumers(t *testing.T) {
+	consumers := []AutogenConsumerConfig{
+		{ID: "parts-a", Mode: "parts_rows"},
+		{ID: "parts-b", Mode: "parts_rows"},
+	}
+	if failures := validateAutogenConsumerSources(consumers); len(failures) == 0 {
+		t.Fatal("expected error for two parts_rows consumers")
+	}
+	single := []AutogenConsumerConfig{{ID: "parts", Mode: "parts_rows"}}
+	if failures := validateAutogenConsumerSources(single); len(failures) != 0 {
+		t.Fatalf("single parts_rows consumer must validate, got %v", failures)
+	}
+}
+
 func loadAndValidate(root string) error {
 	proj, err := Load(root)
 	if err != nil {