refactor(client): replace the per-field settings preference controller with a namespace settings scope

bindSettingsScope mirrors the Host-side settings owner seam in the browser:
one scope per namespace publishes a snapshot store (status, section value,
revision, writability, host/memory mode), validates sections against the
namespace's serialized wire schema via dsh-client-schema-form, and keeps the
controller's listener-before-read, revisioned serialized writes, latest-wins
publication, conflict recovery, and disposal quiescence. Theme, locale, and
busy-Enter services now take the scope as a constructor collaborator, which
removes the bindPersistence/syncPreference two-phase callback pair and the
defaulted no-op persist writers; hand-written wire guards fall away in favor
of the registered schema. test-runtime gains a stubSettingsScope double.

pnpm-lock.yaml

@@ -1351,6 +1351,9 @@ importers:
       '@deepseek-ai/dsh-client-connection':
         specifier: workspace:^
         version: link:../connection
+      '@deepseek-ai/dsh-client-schema-form':
+        specifier: workspace:^
+        version: link:../schema-form
       '@deepseek-ai/dsh-client-ui-slots':
         specifier: workspace:^
         version: link:../ui-slots
@@ -1400,6 +1403,9 @@ importers:
       cordis:
         specifier: ^4.0.0-rc.7
         version: link:../../../vendor/cordis
+      schemastery:
+        specifier: ^3.18.0
+        version: link:../../../vendor/schemastery
 
   packages/client/schema-form:
     dependencies: