fix(theme): resolve nav/login kit issues + bump 0.2.1 -> 0.3.0

Addresses ZB.MOM.WW.Theme/themeissues.md:
- #1 NavRailSection <summary> renders aria-expanded (SSR from Expanded),
  kept in sync by nav-state.js on restore + toggle.
- #2 nav-state.js auto-expands the section holding a.rail-link.active
  (transient via data-zbnav-transient — does not overwrite saved state).
- #3 nav-state.js re-applies on Blazor 'enhancedload' (idempotent via
  per-element init guard).
- #5 LoginCard wraps product in span.login-product + optional Heading
  override param.
- #4 documented as an accepted client-only-persistence tradeoff (no code change).

+4 bUnit tests (48 total, all green).

ZB.MOM.WW.Theme/Directory.Build.props

@@ -4,7 +4,7 @@
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <LangVersion>latest</LangVersion>
-    <Version>0.2.1</Version>
+    <Version>0.3.0</Version>
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
   </PropertyGroup>
 </Project>