indexer: clear duplicate scan cache (folder + global) at the end of
every do_index so stale groups are never presented after a reindex;
previously a file modified or replaced on disk would still appear as a
duplicate candidate from the cached result until a manual rescan
db/vector: replace timestamp-based HNSW revision with a monotonically
incremented integer counter (app_kv.embedding_revision); mark_embedding_ready
atomically increments the counter so two embeddings saved within the same
second correctly advance the revision; get_embedding_revision now reads
this counter instead of MAX(embedding_updated_at), preventing the HNSW
cache from serving stale vectors after same-second batch updates
LyAhn
20c43d2056