On Windows, strip_prefix preserves backslashes, so the non-recursive
branch was looking up tags for 'Melissa\img1.jpg' while tagged_photo
stores 'Melissa/img1.jpg' — every file was filtered out. Normalize to
'/' to match the watcher and populate_knowledge.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>