chore(#366): harden dev test dependencies

.github/dependabot.yml

@@ -11,17 +11,14 @@ updates:
     groups:
       dev-dependencies:
         dependency-type: development
-    # Defer the Vitest 4 migration: @vitest/coverage-v8 v4 measures coverage
-    # differently and drops the suite below the 100%/90% per-file gate even with
-    # all tests passing. Stay on 2.x (and matching happy-dom) until that migration
-    # is done deliberately; minors/patches still flow.
+    # Defer the tracked Vitest 4 migration (#372): its V8 coverage remapping
+    # changes the existing per-file results, so it needs a deliberate coverage
+    # compatibility pass. Stay on the audited 3.x line; minors/patches flow.
     ignore:
       - dependency-name: "vitest"
         update-types: ["version-update:semver-major"]
       - dependency-name: "@vitest/coverage-v8"
         update-types: ["version-update:semver-major"]
-      - dependency-name: "happy-dom"
-        update-types: ["version-update:semver-major"]
   - package-ecosystem: github-actions
     directory: "/"
     schedule:

CHANGELOG.md

@@ -10,6 +10,10 @@ auto-generated per-PR notes; this file is the curated, human-readable history.
 ## [Unreleased]
 
 ### Fixed
+- **Hardened the development test stack** (#366). Vitest and its V8 coverage
+  provider now use the patched 3.2.x line, Happy DOM now uses 20.11.0, and the
+  lockfile resolves the patched transitive dependency graph. `npm audit` is
+  clean; the change affects local/CI tooling only, never the shipped artifact.
 - **Dashboard tiles now respect an explicit saved `view: "table"`** (#368).
   The compatibility form resolves to a Table base presentation before runtime
   panel detection, while an explicit `panel` and its variants/overrides retain