Exclude AppleDouble companions from test discovery (#11)

PLAYTEST_NOTES.md

@@ -5765,3 +5765,17 @@ result is claimed. The source browser build stops at missing ignored Manastorm
 assets; browser release/visual verification remains open. Native offline gear
 persistence, recovery presentation and authenticated RoM progression remain
 under #124. See docs/GAME_GEAR_NAMESPACES.md and gear-namespace-validation.json.
+
+## AppleDouble input discovery — shared #11 (2026-10-10)
+
+Vitest defaults now exclude ._-prefixed file/directory components while retaining
+its built-in exclusions. A portable fresh-fixture proof reproduces three binary
+sidecar transform failures in the unfiltered control; fixed defaults run both
+ordinary sentinels, including ordinary._fragment.test.ts. TypeScript API/CLI
+retain those two inputs. TypeScript 5.8 already skipped dot-prefixed roots, so
+its explicit exclusions preserve observed behavior. Vite/Node config typecheck
+passes. See docs/METADATA_DISCOVERY.md and metadata-discovery-validation.json.
+
+This is source tooling; no native runtime install or new dungeon entry was
+performed. No observed Cellblock Rush boss, GPU capture, full app build,
+gameplay or balance certification is claimed. Existing metadata is retained.