docker_watchdog: skip required containers stopped cleanly or explicitly paused

Exit code 0 on a required container (docker stop, UI stop) now reads as
intentional — no strike, no restart. Non-zero exits still trigger the
existing strike → restart path.

Adds --pause / --resume management commands and a persistent intentional-
stops state file for maintenance windows where even the exit-code heuristic
isn't enough. Containers auto-cleared from the list when seen running again.

Deployment/master.conf.template

@@ -1404,6 +1404,7 @@
 # ━━━ State Files ━━━
     SYS_WATCHDOG_STATE_FILE="$STATE_DIR/system_watchdog_state.db"
     DOCKER_WATCHDOG_FAILED_FILE="$STATE_DIR/docker_watchdog_failed.db"
+    DOCKER_WATCHDOG_INTENTIONAL_FILE="$STATE_DIR/docker_intentional_stops.db"
     SYS_WATCHDOG_REBOOT_LOG="$STATE_DIR/system_watchdog_reboots.db"
     SYS_WATCHDOG_OOM_FILE="$STATE_DIR/system_watchdog_oom.db"