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.Web/Components/Pages/Report.razor

@@ -8,6 +8,7 @@
 @inject AuthenticationStateProvider AuthenticationStateProvider
 @inject ILogger<Report> Logger
 @inject IJSRuntime JSRuntime
+@inject IAuditService AuditService
 
 <PageTitle>Verification Report - TrueCV</PageTitle>
 
@@ -546,6 +547,10 @@
                 {
                     _errorMessage = "Unable to load the report data.";
                 }
+                else
+                {
+                    await AuditService.LogAsync(_userId, AuditActions.ReportViewed, "CVCheck", Id, $"Score: {_report.OverallScore}");
+                }
             }
         }
         catch (Exception ex)