feat: Migrate admin UI from Blazor WASM/MudBlazor to Razor Pages/Cookie Auth/Tabler

- Remove QuantEngine.Web.Client from .sln (keep on disk for reference)
- Replace Blazor Interactive WebAssembly with server-rendered Razor Pages
- Implement Cookie Authentication (HttpOnly, SameSite=Lax, 12h expiry)
- Add AuthService with BCrypt password hashing + auto-migration from SHA-256
- Implement IpLockoutService (3 strikes → 15-min ban)
- Create Admin folder structure with Layout + shared partials
- Implement Dashboard, Collection, Users index pages (base structure)
- Remove hardcoded backdoors (master_recovery, dev auth bypass)
- Remove hardcoded localhost:5265 URLs
- Add Tabler UI base styling (Bootstrap 5 CDN + custom admin.css)
- Update CLAUDE.md with new UI standards and auth policies
- Build: 0 errors, 0 warnings (ready for dev testing)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/dotnet/QuantEngine.Web/QuantEngine.Web.csproj

@@ -4,7 +4,6 @@
     <ProjectReference Include="..\QuantEngine.Infrastructure\QuantEngine.Infrastructure.csproj" />
     <ProjectReference Include="..\QuantEngine.Application\QuantEngine.Application.csproj" />
     <ProjectReference Include="..\QuantEngine.Core\QuantEngine.Core.csproj" />
-    <ProjectReference Include="Client\QuantEngine.Web.Client.csproj" />
   </ItemGroup>
 
   <ItemGroup>
@@ -13,9 +12,9 @@
     <PackageReference Include="Hangfire.Core" Version="1.8.23" />
     <PackageReference Include="Hangfire.MemoryStorage" Version="1.8.1.2" />
     <PackageReference Include="Hangfire.PostgreSql" Version="1.20.10" />
-    <PackageReference Include="MudBlazor" Version="9.0.0" />
+    <PackageReference Include="BCrypt.Net-Next" Version="4.0.3" />
+    <PackageReference Include="FluentValidation.DependencyInjectionExtensions" Version="11.11.0" />
     <PackageReference Include="Serilog.AspNetCore" Version="10.0.0" />
-    <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Server" Version="10.0.0" />
   </ItemGroup>
 
   <ItemGroup>