feat(scripting): PE cache, quarantine-race fix, recovery, readiness for the out-of-process runner (lmxopcua#780 P1)

Second P1 slice of docs/plans/2026-11-09-out-of-process-script-runner-design.md; still opt-in behind
Scripting:Runner=OutOfProcess (InProcess unchanged).

- Compiled-PE cache (design §7, §14 #8): Scripting:Worker:PeCacheDir holds <dir>/pe/<id>.pe entries authenticated
  with HMAC-SHA256 under a per-node random key (<dir>/pe-cache.key, created by the host, 0600/0700 on Unix), handed to
  the worker in Hello. Entry id = SHA-256(compile fingerprint + kind + source); the fingerprint covers the Roslyn
  version, the Core.Scripting build (analyzer, wrapper, stack guard), the sandbox reference set and the runtime. Edited,
  truncated, other-key or renamed entries are rejected, deleted and recompiled; the worker never loads unverified bytes.
  Pruned by recency at startup (30 d / 50 000). ScriptEvaluator splits into CompileToImage + FromImage. Measured on
  40 scripts, restart to every first result: macOS 820 ms no cache / 840 ms empty / 85 ms warm;
  windev (Windows) 9.5 s / 9.4 s / 1.0 s.
- Quarantine race: WorkerConnection runs exit attribution synchronously BEFORE completing the evaluations/loads it held
  (and before Exited), and the shard passes it straight to the runner — a kill strike is in place before the killed
  key's slot is released.
- Supervision: a dead worker restarts by itself after its backoff; Unavailable outcomes carry ScriptRunOutcome.Recovery
  (-> VirtualTagEvalResult.RetryWhen) and the VT actor / Calculation driver re-evaluate once against current inputs when
  it completes. Isolation worker stops after Scripting:Worker:IsolationIdleTimeout (10 min). Keys compiling when a
  worker dies are suspects too (isolation finds a poison compile and quarantines it). Startup orphan sweep by launch
  marker: kills only a process whose marker's host is gone and whose pid + start time + image match.
- Crash-loop circuit (Scripting:Worker:CircuitOpenAfter, 2 min): runner Unavailable, one Error, evaluations answered
  at once while shards keep retrying at the cap.
- Observability (§10): otopcua.script.runner.state, worker.up/inflight/queue_depth/heap_bytes (shard),
  ipc.roundtrip + eval.duration (kind), compile{cache}, isolation.suspects, exits reason=idle. `script-runner` health
  check on the ready tier, at worst Degraded (§14 #12: degraded but still ready).

Left on #780: self-contained worker publish, installer (account, pipe ACL, firewall), docker-dev live drill,
scripted-alarm seam, the §4.5 per-seam batch submit, the §8 perf harness.

Tests: SupervisionTests, PeCacheStoreTests/PeCacheWorkerTests (real workers), ScriptRunnerHealthCheckTests, VT + Calc
recovery seam tests; 14 mutations each turned their test red.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

docs/ServiceHosting.md

@@ -94,7 +94,11 @@ Off by default. When enabled, a driver node launches up to `Scripting:Worker:Sha
 (`ZB.MOM.WW.OtOpcUa.ScriptWorker`, from `script-worker/` beside the host) on its first compiled script evaluation and
 kills them with it: a Job Object with kill-on-close on Windows, pipe end of stream plus a parent-pid poll elsewhere,
 and a Shutdown frame then a kill on host stop. Their stderr lands in the host log prefixed `ScriptWorker[<shard>]`.
-The worker currently runs under the host's account through the dotnet muxer; the dedicated low-privilege account,
+At startup the host kills workers a dead predecessor of the same install left behind, matched by launch marker
+(pid + start time + image, and only when the marker's host is gone). `Scripting:Worker:PeCacheDir`, when set, holds the
+compiled-PE cache, its HMAC key and the launch markers: put it outside the install folder (startup refuses a relative path
+or one inside the content root) on a directory only the service account can read. The `script-runner` readiness component
+is at worst Degraded. The worker currently runs under the host's account through the dotnet muxer; the dedicated low-privilege account,
 pipe ACL and firewall outbound rule (design §14 #5/#6) are installer work still open on lmxopcua#780. See
 `docs/VirtualTags.md` §"Out-of-process runner".