Add audit logging, processing stages, delete functionality, and bug fixes

- Add audit logging system for tracking CV uploads, processing, deletion,
  report views, and PDF exports for billing/reference purposes
- Add processing stage display on dashboard instead of generic "Processing"
- Add delete button for CV checks on dashboard
- Fix duplicate primary key error in CompanyCache (race condition)
- Fix DbContext concurrency in Dashboard (concurrent delete/load operations)
- Fix ProcessCVCheckJob to handle deleted records gracefully
- Fix duplicate flags in verification report by deduplicating on Title+Description
- Remove internal cache notes from verification results
- Add EF migrations for ProcessingStage and AuditLog table

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

src/TrueCV.Infrastructure/Services/CVCheckService.cs

@@ -18,17 +18,20 @@ public sealed class CVCheckService : ICVCheckService
     private readonly ApplicationDbContext _dbContext;
     private readonly IFileStorageService _fileStorageService;
     private readonly IBackgroundJobClient _backgroundJobClient;
+    private readonly IAuditService _auditService;
     private readonly ILogger<CVCheckService> _logger;
 
     public CVCheckService(
         ApplicationDbContext dbContext,
         IFileStorageService fileStorageService,
         IBackgroundJobClient backgroundJobClient,
+        IAuditService auditService,
         ILogger<CVCheckService> logger)
     {
         _dbContext = dbContext;
         _fileStorageService = fileStorageService;
         _backgroundJobClient = backgroundJobClient;
+        _auditService = auditService;
         _logger = logger;
     }
 
@@ -66,6 +69,8 @@ public sealed class CVCheckService : ICVCheckService
             "CV check {CheckId} created for user {UserId}, processing queued",
             cvCheck.Id, userId);
 
+        await _auditService.LogAsync(userId, AuditActions.CVUploaded, "CVCheck", cvCheck.Id, $"File: {fileName}");
+
         return cvCheck.Id;
     }
 
@@ -150,6 +155,33 @@ public sealed class CVCheckService : ICVCheckService
         }
     }
 
+    public async Task<bool> DeleteCheckAsync(Guid checkId, Guid userId)
+    {
+        _logger.LogDebug("Deleting CV check {CheckId} for user {UserId}", checkId, userId);
+
+        var cvCheck = await _dbContext.CVChecks
+            .Include(c => c.Flags)
+            .FirstOrDefaultAsync(c => c.Id == checkId && c.UserId == userId);
+
+        if (cvCheck is null)
+        {
+            _logger.LogWarning("CV check {CheckId} not found for user {UserId}", checkId, userId);
+            return false;
+        }
+
+        var fileName = cvCheck.OriginalFileName;
+
+        _dbContext.CVFlags.RemoveRange(cvCheck.Flags);
+        _dbContext.CVChecks.Remove(cvCheck);
+        await _dbContext.SaveChangesAsync();
+
+        _logger.LogInformation("Deleted CV check {CheckId} for user {UserId}", checkId, userId);
+
+        await _auditService.LogAsync(userId, AuditActions.CVDeleted, "CVCheck", checkId, $"File: {fileName}");
+
+        return true;
+    }
+
     private static CVCheckDto MapToDto(CVCheck cvCheck)
     {
         return new CVCheckDto
@@ -158,6 +190,7 @@ public sealed class CVCheckService : ICVCheckService
             OriginalFileName = cvCheck.OriginalFileName,
             Status = cvCheck.Status.ToString(),
             VeracityScore = cvCheck.VeracityScore,
+            ProcessingStage = cvCheck.ProcessingStage,
             CreatedAt = cvCheck.CreatedAt,
             CompletedAt = cvCheck.CompletedAt
         };