test(wasm): close mutation package gate

Run browser-backed mutest sequentially without a parent jobserver, disable Firefox background work, batch replay projections while preserving ordered application, and elect a 250 ms budget for the durable 64-command browser fixture. All four hemx-wasm shards pass with 59 mutants and no survivors, closing the mutation matrix.

req: test/004

req: test/020

req: test/021

req: performance/005

req: performance/007

req: v1_release/006

docs/v1-readiness.md

@@ -17,11 +17,13 @@ closure. Their implementation order lives in `PLAN.md`. req: examples/001 req: p
   rollback-safe persistence, restart recovery, health/readiness, diagnostics,
   metrics, CSP, and mixed-build fail-closed recovery proven.
 - V1 closure matrix: not closed. The recorded local workspace, browser,
-  performance, docs, and example gates pass, and warning-denied vulnerability
-  and source audits are clean. Strict license closure still awaits a repository
-  license allowlist, and the mutation-testing release gate is only partially
-  classified. These open gates block a feature-complete or production-ready
-  claim. req: test/020 req: test/021 req: v1_release/006
+  performance, docs, and example gates pass, warning-denied vulnerability and
+  source audits are clean, and the mutation-applicable library/proc-macro matrix
+  has no unexplained survivors. Strict license closure still awaits an owner-chosen
+  license for 20 currently unlicensed workspace packages and an allowlist decision
+  for Apache-2.0, Apache-2.0 WITH LLVM-exception, BSD-3-Clause, BSL-1.0, MIT,
+  Unicode-3.0, and Unlicense dependencies; this blocks a production-ready claim.
+  req: test/020 req: test/021 req: v1_release/006
 - Publishing and deployment: explicitly unauthorized.
 
 ## Baseline evidence