extract jobkit-daemon library from poc-memory daemon

Create jobkit-daemon crate with generic daemon infrastructure:
- event_log: JSONL append with size-based rotation
- socket: Unix domain socket RPC client and server with signal handling
- status: JSON status file read/write

Migrate daemon.rs to use the library:
- Worker pool setup via Daemon::new()
- Socket loop + signal handling via Daemon::run()
- RPC handlers as registered closures
- Logging, status writing, send_rpc all delegate to library

Migrate tui.rs to use socket::send_rpc() instead of inline UnixStream.

daemon.rs: 1952 → 1806 lines (-146), old status_socket_loop removed.
tui.rs: socket boilerplate removed.

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

poc-memory/Cargo.toml

@@ -20,6 +20,7 @@ rayon = "1"
 peg = "0.8"
 paste = "1"
 jobkit = { git = "https://evilpiepirate.org/git/jobkit.git/" }
+jobkit-daemon = { path = "../jobkit-daemon" }
 redb = "2"
 log = "0.4"
 ratatui = "0.29"