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.Application/Models/EducationVerificationResult.cs

@@ -0,0 +1,22 @@
+namespace TrueCV.Application.Models;
+
+public sealed record EducationVerificationResult
+{
+    public required string ClaimedInstitution { get; init; }
+    public string? MatchedInstitution { get; init; }
+    public required string Status { get; init; }  // Recognised, NotRecognised, DiplomaMill, Suspicious, Unknown
+    public bool IsVerified { get; init; }
+    public bool IsDiplomaMill { get; init; }
+    public bool IsSuspicious { get; init; }
+    public string? VerificationNotes { get; init; }
+
+    // Date plausibility
+    public DateOnly? ClaimedStartDate { get; init; }
+    public DateOnly? ClaimedEndDate { get; init; }
+    public bool DatesArePlausible { get; init; } = true;
+    public string? DatePlausibilityNotes { get; init; }
+
+    // Qualification info
+    public string? ClaimedQualification { get; init; }
+    public string? ClaimedSubject { get; init; }
+}