config: watch config.json5 with inotify, reload live on change

Both config halves (Config for the memory section, AppConfig globally)
are now reloaded whenever ~/.consciousness/config.json5 changes on
disk. So edits from vim, manual tweaks, or F6's own config_writer
calls all land without a restart. No more "reload the daemon to pick
up a config change."

Wires up the previously-unused Config::reload() (Kent flagged it as
"not dead, just not wired"). Pairs it with an AppConfig reload via
install_app(). Both run on the same file-change event.

Implementation:

- notify-debouncer-mini watches the config file's parent directory
  (editors usually replace-via-rename, so watching the file itself
  misses the new inode). Debounced at 200ms to coalesce the flurry
  of events editors produce around a single save.
- Filter for events whose path is the actual config file.
- On match: call reload() for Config, run build_figment + extract for
  AppConfig. If AppConfig parsing fails (editor mid-save with partial
  content), log and keep the old cached value.
- Watcher runs in its own named thread, fire-and-forget. If startup
  fails we just log and move on — worst case is no live reload, not
  a crash.

CliArgs + SubCmd both get Clone derives so the watcher can own a
snapshot of the startup args for future reloads. Watcher is kicked
off in user/mod.rs:start() right after load_session.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

Cargo.toml

@@ -30,6 +30,7 @@ log = "0.4"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 json-five = "0.3"
+notify-debouncer-mini = "0.7"
 
 ratatui = { version = "0.30", features = ["unstable-rendered-line-info"] }
 tui-markdown = { git = "https://github.com/koverstreet/tui-markdown", subdirectory = "tui-markdown" }