feat: add omp (Oh My Pi) harness adapter

[Boxyboxy]

What

Adds omp (Oh My Pi) as a sixth verified firstmate harness adapter, alongside claude, codex, opencode, pi, and grok. Firstmate can now detect when it is itself running on omp (previously mis-detected as claude), and can spawn / supervise / steer / recover / tear down omp crewmates and secondmates, hold its session lock under omp, and run its own primary turn-end guard + watcher supervision under omp.

Why omp is distinct (not just "pi")

omp is Pi-derived but differs in ways that matter to the adapter:

• Sets both OMPCODE=1 and CLAUDECODE=1, so detection must check OMPCODE first or omp mis-detects as claude.
• Runs as process omp, so it supports confident secondmate liveness (pi's bare node does not).
• Has a real approval system, so unattended crewmates need --auto-approve.
• .omp/extensions/*.ts is a native auto-discovery root, so the primary turn-end guard is a tracked, auto-discovered extension (no -e wiring, no generated bridge like pi needs).
• Exposes an active session_stop hook that forces a continuation by returning {continue:true}, making omp a direct-blocking turn-end harness (class with claude/codex) - a third mechanism distinct from the passive follow-up used by pi/grok/opencode.

Surface

• Detection (fm-harness.sh), lock (fm-lock.sh), spawn mechanics + crewmate turn-end signal extension (fm-spawn.sh).
• Busy detection (fm-watch.sh, fm-tmux-lib.sh), liveness (bin/backends/tmux.sh).
• Bootstrap dispatch/effort/secondmate-liveness (fm-bootstrap.sh), session-start guard load-health (fm-session-start.sh), teardown cleanup (fm-teardown.sh).
• Primary turn-end guard: new tracked .omp/extensions/fm-primary-turnend-guard.ts (session_stop); classification comment + repair_line arm; new docs/supervision-protocols/omp.md; docs/turnend-guard.md.
• Knowledge: harness-adapters skill omp section + an expanded new-adapter wiring checklist so future adapters are fully wired; verified-set enumerations across AGENTS.md, README.md, docs, and the afk skill.
• Tests: new tests/fm-omp-harness.test.sh and tests/fm-lock.test.sh, plus coverage in bootstrap/teardown/turnend-guard/supervision/liveness; tests/lib.sh now clears ambient harness markers so detection is hermetic across dev machines.

How it was built

Spec-first: a frozen spec was authored, then reviewed from four angles in parallel (adapter-integration consistency, version-resilience, correctness/security, test coverage). The review caught real gaps the first draft missed - a fm-lock.sh blocker (an omp primary could not hold its session lock), three separate adapter enumerations in fm-bootstrap.sh, and the repair_line() arm - which were folded into the spec before the parallel implementation.

Verification

• Every omp runtime fact verified live on omp 16.3.12: detection markers, process name, busy signature (⟦esc⟧), /quit exit + resume line, .omp/extensions auto-discovery of a committed file, and session_stop forced continuation (with both a static return and a realistic async handler that awaits a spawned subprocess).
• shellcheck bin/*.sh bin/backends/*.sh tests/*.sh is clean.
• ~25 test files pass locally covering every touched surface plus a regression sweep; 0 failures.

Interrupt (Escape) is inferred from omp's own ⟦esc⟧ hint rather than cleanly observed; a re-confirm item is recorded in the skill's re-verification checklist.