Doc Review: add-state-loop-lock

Reviewed docs touched by or referring to the fix.

Files reviewed

CHANGELOG.md — added ### Added — .state.loop file lock (task add-state-loop-lock) at the top of [unreleased] covering R1-R7 + D-L1 through D-L6, the env-var mechanism, callsites wrapped in both scripts, the test plan, the adversarial findings, backwards-compat, stdlib-only constraint, and 447-passing count.
AGENTS.md — added a .state.lock (v1.1) bullet under State Enforcement — Loops (v1) summarizing the lock shape, granularity, blocking-acquire behavior, env-var mechanism, and pointer to the technical doc.
README.md — extended the Loop Engineering runtime paragraph with a single sentence pointing at .state.lock serialization with a design/loops/technical.md §7 pointer.
design/loops/technical.md §7 — added a new "Lock serialization" subsection covering the lock shape, callsites in both scripts, the env-bypass mechanism (D-L6), the re-entry forbidding audit, and the harness-contractor-loop-control implication.
contracts/harness-integration.md — no edits. The A4 follow-up "forbid loop-control commands inside a tick" is deferred to a small docs-only follow-up (not a blocker); listed in the design doc. Did NOT modify the harness integration contract in this task to avoid scope-creep.
prompts/loop-*.md — no edits (phase prompts are content; no locking references there).
scripts/install.sh / scripts/update.sh / scripts/upgrade.sh — no edits (don't touch the lock).

rg "_loop_lock|\.state\.lock|AUTOMATON_NO_LOOP_LOCK" design/ templates/ scripts/ contracts/ README.md AGENTS.md prompts/ — all hits intentional.
rg "fcntl|msvcrt|flock" design/loops/technical.md AGENTS.md README.md — only intentional references in the new docs.
The add-loop-runner/ v1 CHANGELOG entry still says "the runner writes .state.loop atomically via _write_state_loop (tmp file then replace)" — this remains accurate (the atomic write is still in place; the lock adds a coarse mutex on top — defense-in-depth per D-L5).

PASS — proceed to referee.