Add Azure Blob Storage archive & email safety net

- Add AzureBlobStorageService, DocumentArchiveSyncService, and related config for secondary PDF archiving of invoices/reminders
- Add SQL procs and schema changes for archive backfill
- Update invoice/reminder services to upload PDFs to blob storage
- Add telemetry counters and unit tests for blob storage/archive logic
- Add Fuchs:Email:OverrideRecipient config and enforce dev/test email redirect in ProcessWebComService, with tests
- Improve JS date parsing (German formats), stricter JSON date detection
- Increase widget SQL timeouts, update dependencies, docs, and project files

Fuchs/Observability/FuchsTelemetry.cs

@@ -1,4 +1,4 @@
-using System.Diagnostics;
+using System.Diagnostics;
 using System.Diagnostics.Metrics;
 
 namespace Fuchs.Observability;
@@ -41,6 +41,10 @@ public static class FuchsTelemetry
         Meter.CreateCounter<long>("fuchs.banking.mt940.rows", "{row}", "Number of MT940 transaction lines parsed.");
     public static readonly Counter<long> MfrCalls =
         Meter.CreateCounter<long>("fuchs.mfr.calls", "{call}", "Number of MFR ERP client calls initiated.");
+    public static readonly Counter<long> BlobUploadsSucceeded =
+        Meter.CreateCounter<long>("fuchs.blobstorage.uploads", "{upload}", "Number of documents successfully archived to Azure Blob Storage.");
+    public static readonly Counter<long> BlobUploadsFailed =
+        Meter.CreateCounter<long>("fuchs.blobstorage.uploads.failed", "{upload}", "Number of documents that failed to archive to Azure Blob Storage.");
 
     // ── Performance histograms (durations in milliseconds) ───────────────────
     public static readonly Histogram<double> PdfRenderDuration =