docs: drop soak + 2-week-pilot as PR 7.2 preconditions

The parity matrix gate is the precondition for retiring the legacy
Galaxy projects. The 24h × 50k soak run and 2-week production pilot
were sketched in early planning as additional safety nets but aren't
operationally applicable for this deployment — there's no separate
production fleet to pilot against, and the soak harness's value is as
ongoing diagnostic infrastructure (still shipped in PR 6.4) rather
than a one-shot release gate.

PR 7.2's only remaining precondition is the matrix being fully green
or carrying documented accepted-deltas — verified 2026-04-30 on the
dev rig: 14 passed / 1 skipped / 0 failed.

Affected:
- docs/v2/Galaxy.ParityMatrix.md "Outstanding deltas" — flips to
  "PR 7.2 is unblocked"
- docs/v2/Galaxy.ParityRig.md "After the rig is green" — drops the
  three-step soak+pilot flow, keeps only the matrix-doc bookkeeping
  follow-up
- lmx_mxgw_impl.md PR 7.2 "Depends on" — replaces "fully soaked"
  with the matrix-green precondition + the verification date

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

docs/v2/Galaxy.ParityMatrix.md

@@ -124,8 +124,8 @@ suite skips or tolerates them by design.
 ## Outstanding deltas
 
 None as of 2026-04-30. Phase 7 (PR 7.1) flipped the default to
-`mxgw`; PR 7.2 retires the legacy projects after the soak run + a
+`mxgw`; PR 7.2 (legacy project deletion) is unblocked — the matrix
-2-week production pilot.
+gate is satisfied and no further soak/pilot precondition applies.
 
 ## Running the matrix
 

docs/v2/Galaxy.ParityRig.md

@@ -355,14 +355,7 @@ Galaxy with a script that imports 50k attributes onto a generated UDO
 
 ## After the rig is green
 
-Three further steps before PR 7.2 lands:
+When the matrix is fully green or carries documented accepted-deltas,
-
+PR 7.2 (legacy project deletion) is unblocked. The only follow-up is
-1. Promote any newly-discovered accepted-delta to the matrix doc with
+to promote any newly-discovered accepted-delta to the matrix doc with
-   the why.
+the why so the matrix history stays auditable.
-2. Run the full 24h × 50k soak (or compressed tag count if Galaxy isn't
-   that big) and link the stdout log in the PR description.
-3. Pilot the default flip (PR 7.1's `Galaxy.DefaultBackend = "GalaxyMxGateway"`)
-   on a single production node for ~2 weeks. Watch the OTel/metrics
-   surface (`docs/v2/Galaxy.Performance.md`) for regressions.
-
-Then 7.2 has the rollback-risk evidence its precondition asks for.

lmx_mxgw_impl.md

@@ -913,7 +913,9 @@ after 6.4 (uses its data). 6.W last.
   - `Server/Configuration/DriverFactoryRegistry.cs` — remove the
     `legacy-host` switch arm.
 
-**Depends on:** PR 7.1 fully soaked (no rollback risk).
+**Depends on:** parity matrix in `docs/v2/Galaxy.ParityMatrix.md` is
+fully green or carries documented accepted-deltas (verified
+2026-04-30 on the dev rig: 14 passed / 1 skipped / 0 failed).
 
 #### PR 7.3 — Doc + memory housekeeping