Watch backend sessions

Read Watchdog behavior completely. Start only after the user explicitly names Meta-O watchdog or mo-watchdog; a generic monitoring question does not activate this skill.

Use scripts/mo-watchdog.sh target --backend orca --session <id> for one session or scripts/mo-watchdog.sh scan for all reachable Orca sessions. Observation is read-only. An explicit nudge additionally requires --nudge <message> and exact target authorization; the script re-reads native state and suppresses the nudge when that state changed. It reserves a bounded private digest before delivery and suppresses the same message, an ambiguous attempt, or a saturated unchanged state across later invocations. Nudges return after native delivery; agent completion is observed separately.

Treat malformed or stale native state as a typed unsafe observation: report it, fail closed, and do not nudge or guess the target state.