feat: unified fleet CLI, Main Chat preservation policy, sidechat routing, and file transfers

- Added CHAT_POLICY.md and README.md banner enforcing sidechat-first and file-transfer-first rules.
- Added strict Main Chat block to super dm send and super dm wo with --allow-main-chat override.
- Implemented file transfer staging and metadata registry in super dm send-file and super dm files (with clean subcommand).
- Added full job lifecycle management (show, create, enable, disable, delete, run --follow) to super-cli.py and box-ctl.py.
- Audited all jobs in jobs/*.json and redirected automated dispatches away from Main Chat.
- Hardened chromebox-watchdog.sh with systemd user session environment exports and stale singleton cleanup.
- Added compose_check command choice to muse-chat-api.py.

bin/chromebox-watchdog.sh

@@ -8,6 +8,8 @@
 # recover-after-rebuild.sh philosophy.
 # Runs every 2 min via systemd timer chromebox-watchdog-<profile>.timer.
 set -euo pipefail
+export XDG_RUNTIME_DIR="${XDG_RUNTIME_DIR:-/run/user/$(id -u)}"
+export DBUS_SESSION_BUS_ADDRESS="${DBUS_SESSION_BUS_ADDRESS:-unix:path=${XDG_RUNTIME_DIR}/bus}"
 # Prevent overlapping runs: the timer fires every 2 min but a relaunch
 # (kill + sleep 25 + chrome startup + page load) can exceed that, and two
 # concurrent runs kill each others chrome (observed 2026-10-03: pip flapped
@@ -92,6 +94,11 @@ fi
 pat="profiles/${PROFILE:0:${#PROFILE}-1}[${PROFILE: -1}]/"
 pkill -f "chromium.*$pat" 2>/dev/null || true
 sleep 3
+# Clean up stale singleton symlinks that break subsequent browser startup
+rm -f "/home/super/.local/share/chrome-box/profiles/${PROFILE}/home/.config/chromium/SingletonLock" \
+      "/home/super/.local/share/chrome-box/profiles/${PROFILE}/home/.config/chromium/SingletonSocket" \
+      "/home/super/.local/share/chrome-box/profiles/${PROFILE}/home/.config/chromium/SingletonCookie" 2>/dev/null || true
+
 # Relaunch in its own systemd scope so it survives this oneshot run.
 # nohup/setsid do NOT escape: this timer's service uses KillMode=control-group
 # and systemd SIGKILLs everything in the cgroup at teardown (observed