feat: tower session — persistent Hermes ↔ Timmy conversation loop

Two-pane tmux session with file-based message passing:
- tower-hermes.sh: Hermes side (cloud/Claude)
- tower-timmy.sh: Timmy side (HERMES_HOME=~/.timmy)
- tower-watchdog.sh: self-healing, restarts dead panes
- tower-session.sh: tmux bootstrap script

Communication via ~/.tower/*.msg files.
Both agents maintain named sessions (tower-hermes, tower-timmy)
for conversation continuity across restarts.

.gitignore

@@ -62,6 +62,9 @@ bin/*
 !bin/hermes-dispatch
 !bin/hermes-enqueue
 !bin/hermes-config-sync
+!bin/tower-hermes.sh
+!bin/tower-timmy.sh
+!bin/tower-watchdog.sh
 
 # ── Queue (transient task queue) ─────────────────────────────────────
 queue/