Add UK education verification and security fixes

Features:
- Add UK institution recognition (170+ universities)
- Add diploma mill detection (100+ blacklisted institutions)
- Add education verification service with date plausibility checks
- Add local file storage option (no Azure required)
- Add default admin user seeding on startup
- Enhance Serilog logging with file output

Security fixes:
- Fix path traversal vulnerability in LocalFileStorageService
- Fix open redirect in login endpoint (use LocalRedirect)
- Fix password validation message (12 chars, not 6)
- Fix login to use HTTP POST endpoint (avoid Blazor cookie issues)

Code improvements:
- Add CancellationToken propagation to CV parser
- Add shared helpers (JsonDefaults, DateHelpers, ScoreThresholds)
- Add IUserContextService for user ID extraction
- Parallelized company verification in ProcessCVCheckJob
- Add 28 unit tests for education verification

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

src/TrueCV.Web/Components/Pages/Account/Register.razor

@@ -48,7 +48,7 @@
                             <InputText id="password" type="password" class="form-control form-control-lg"
                                        @bind-Value="_model.Password" placeholder="Create a password" />
                             <ValidationMessage For="() => _model.Password" class="text-danger" />
-                            <div class="form-text">Password must be at least 6 characters.</div>
+                            <div class="form-text">Password must be at least 12 characters with uppercase, lowercase, number, and symbol.</div>
                         </div>
 
                         <div class="mb-4">
@@ -153,7 +153,7 @@
         public string Email { get; set; } = string.Empty;
 
         [System.ComponentModel.DataAnnotations.Required(ErrorMessage = "Password is required")]
-        [System.ComponentModel.DataAnnotations.MinLength(6, ErrorMessage = "Password must be at least 6 characters")]
+        [System.ComponentModel.DataAnnotations.MinLength(12, ErrorMessage = "Password must be at least 12 characters")]
         public string Password { get; set; } = string.Empty;
 
         [System.ComponentModel.DataAnnotations.Required(ErrorMessage = "Please confirm your password")]