Adds a per-conversation "delete" with two modes, and removes the per-frame
rescans of the chat history that shared these files.
Delete conversation (header trash icon → confirm dialog):
- Delete (revive-on-new-message): clears local history and tombstones the
messages (new chat_deleted table, keyed dedup hashes) so the every-few-
seconds memo re-scan can't re-import them; a genuinely NEW message (new
txid) revives the thread.
- Delete & block: removes history WITHOUT a tombstone and records the cid as
blocked (settings); ChatService::ingest drops that conversation's messages
— old and future — until unblocked from the "Blocked" manager, which then
re-imports the conversation from chain.
- Local-only (messages remain on-chain; the peer keeps their copy).
deleteConversation() deletes the DB rows FIRST and only then mutates the
store, so a failed write can't leave the two diverged.
Unit-tested (revive / tombstone-survives-reload / block / unblock) and
adversarially reviewed (store/DB divergence, half-open DB, revive-unread).
Performance (chat + badge hot paths, from the perf audit):
- ChatStore gains revision(); the Chat unread badge is now a single O(N)
no-alloc pass cached on it (was O(conversations x messages) copy+sort every
frame). The conversation list and open thread are memoized on revision()
(+ show-hidden and AddressBook::revision() for peer-name resolution).
- AddressBook gains revision() so an in-place contact rename invalidates the
chat memo (an edit keeps entries().size() constant).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>