docs: drop dangling FOCAS refs + link unreferenced v2 design docs

- docs/drivers/FOCAS.md and docs/v2/implementation/focas-wire-protocol.md
  pointed at focas-deployment.md and focas-simulator-plan.md, both of
  which were untracked drafts that have since been removed. Drop the
  refs (the wire-protocol companion now stands on its own; deployment
  guidance lives inline in the FOCAS driver doc).
- Link the orphan v2 design docs from docs/README.md (multi-host
  dispatch, v2 release readiness, the historical lmx-followups tracker)
  and from modbus-test-plan.md (s7.md, mitsubishi.md per-family quirk
  catalogs, sibling to dl205.md).

Surfaced by the doc audit; no content changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/drivers/FOCAS.md

@@ -2,7 +2,6 @@
 
 Getting-started guide for the FANUC FOCAS2 driver. This is the short path — for
 the exhaustive per-node mapping read [`docs/v2/driver-specs.md §7`](../v2/driver-specs.md),
-for deployment details read [`docs/v2/focas-deployment.md`](../v2/focas-deployment.md),
 for the test-harness map read [FOCAS-Test-Fixture.md](FOCAS-Test-Fixture.md).
 
 ## What it talks to
@@ -210,8 +209,9 @@ latency spike once per cadence.
   driver surface via `FakeFocasClient`. Includes the alarm-projection raise /
   clear diffing tests.
 - **Integration tests** — `tests/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.IntegrationTests/`
-  hold the Docker simulator scaffold (Stream B / C of the simulator plan —
-  `docs/v2/implementation/focas-simulator-plan.md`).
+  hold the Docker simulator scaffold; see
+  [`docs/v2/implementation/focas-wire-protocol.md`](../v2/implementation/focas-wire-protocol.md)
+  for what the simulator emits vs. real CNC behaviour.
 - **E2E script** — `scripts/e2e/test-focas.ps1` stages Host + Proxy + a real
   CNC (or the simulator) and exercises connect → read → write → subscribe
   round-trips. See [`docs/drivers/FOCAS-Test-Fixture.md`](FOCAS-Test-Fixture.md)