docs(audit): Modbus-Test-Fixture.md — accuracy pass

STALE-STATUS: TL;DR + Lifecycle section referred to "localhost" as the
simulator address (Modbus-Test-Fixture.md:7,19). Fixture default is
10.100.0.35:5020 (shared Docker host, migrated 2026-04-28) confirmed by
ModbusSimulatorFixture.cs:36.  Updated both prose occurrences.

INLINE COMPLETENESS: Follow-up item 1 claimed MODBUS_SIM_ENDPOINT
lacked documentation; the env var is already documented in this page +
CLAUDE.md. Reworded to reflect actual gap (cross-reference to
test-data-sources.md only).

Verified: python3 .docs-audit/check_links.py — zero rows for this doc.

docs/drivers/Modbus-Test-Fixture.md

@@ -3,11 +3,11 @@
 Coverage map + gap inventory for the Modbus TCP driver's integration-test
 harness backed by `pymodbus` simulator profiles per PLC family.
 
-**TL;DR:** Modbus is the best-covered driver — a real `pymodbus` server on
+**TL;DR:** Modbus is the best-covered driver — a real `pymodbus` server on the
-localhost with per-family seed-register profiles, plus a skip-gate when the
+shared Docker host (`10.100.0.35:5020`) with per-family seed-register profiles,
-simulator port isn't reachable. Covers DL205 / Mitsubishi MELSEC / Siemens
+plus a skip-gate when the simulator port isn't reachable. Covers DL205 /
-S7-1500 family quirks end-to-end. Gaps are mostly error-path + alarm/history
+Mitsubishi MELSEC / Siemens S7-1500 family quirks end-to-end. Gaps are mostly
-shaped (neither is a Modbus-side concept).
+error-path + alarm/history shaped (neither is a Modbus-side concept).
 
 ## What the fixture is
 
@@ -16,8 +16,9 @@ shaped (neither is a Modbus-side concept).
   `tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests/Docker/`.
   Docker is the only supported launch path.
 - **Lifecycle**: `ModbusSimulatorFixture` (collection-scoped) TCP-probes
-  `localhost:5020` on first use. `MODBUS_SIM_ENDPOINT` env var overrides the
+  `10.100.0.35:5020` (the shared Docker host) on first use.
-  endpoint so the same suite can target a real PLC.
+  `MODBUS_SIM_ENDPOINT` env var overrides the endpoint so the same suite can
+  target a real PLC or a locally-running container.
 - **Profiles**: `DL205Profile`, `MitsubishiProfile`, `S7_1500Profile` —
   each composes device-specific register-format + quirk-seed JSON for pymodbus.
   Profile JSONs live under `Docker/profiles/` and are baked into the image.
@@ -102,8 +103,9 @@ Not a Modbus concept. Driver doesn't implement `IAlarmSource` or
 
 ## Follow-up candidates
 
-1. Add `MODBUS_SIM_ENDPOINT` override documentation to
+1. Add `MODBUS_SIM_ENDPOINT` cross-reference to
-   `docs/v2/test-data-sources.md` so operators can point the suite at a lab rig.
+   `docs/v2/test-data-sources.md` (already documented in this page + CLAUDE.md;
+   the v2 page could link here for the complete env-var table).
 2. ~~Extend `pymodbus` profiles to inject exception responses~~ — **shipped**
    via the `exception_injection` compose profile + standalone
    `exception_injector.py` server. Rules in