feat: OpenAI Provider, Key-Checker Quota-Erkennung, persistierte Scanner-Logs

- OpenAI als vollwertiger Chat-Provider (Modell-Auswahl, Key-Routing, StreamChat)
- Hardcoded OpenAI-Modelle im Cache (gpt-5.x, gpt-4.1, o3, o4-mini etc.)
- /api/models/openai Endpoint, OpenAI-Optgroup im Agent-Dropdown
- Key-Routing: OpenAI-Key aus api_keys-Tabelle, Fallback via GetFirstActiveKeyByProvider
- OpenAI-Checker: 2-Schritt-Check (Models + chat/completions mit max_tokens=1)
- Google-Checker: 2-Schritt-Check (Models + generateContent mit maxOutputTokens=1)
- 429 insufficient_quota und billing_not_active korrekt als quota_exceeded erkannt
- Provider-Erkennung beim Adopt via KeyPatterns.DetectType() statt hardcoded anthropic
- HandleCheck/HandleCheckAll unterstützt jetzt Anthropic, OpenAI und Google
- Neue scanner_logs-Tabelle mit details-Spalte (JSON) für strukturierte Auswertung
- GitHubEventScannerService: AddLog persistiert in DB, detaillierte Key-Fund-Logs
- KeyScannerService: AddLog-Methode mit DB-Persistierung, detaillierte Logs
- Frontend: Ungeprüfte-prüfen-Button (sequenziell, stoppt bei valid)
- Frontend: Provider-Indicator im Key-Switch-Modal (Anthropic/OpenAI/Google)
- Frontend: Check-Button für alle Provider (nicht nur Anthropic)

Services/DatabaseService.Integrations.cs

@@ -519,4 +519,48 @@ public partial class DatabaseService
         await conn.ExecuteAsync("UPDATE scanned_keys SET deleted = 1 WHERE scanned_key_id = @scannedKeyId", new { scannedKeyId });
     }
 
+    // ── Scanner Logs ──
+
+    public async Task CreateScannerLog(string type, string message, string scanner = "event", string details = null)
+    {
+        using var conn = CreateConnection();
+        // Sicherstellen dass die details-Spalte existiert (Migration)
+        try
+        {
+            await conn.ExecuteAsync(@"ALTER TABLE scanner_logs ADD COLUMN details TEXT");
+        }
+        catch { /* Spalte existiert bereits */ }
+
+        await conn.ExecuteAsync(@"
+            INSERT INTO scanner_logs (timestamp, type, message, scanner, details)
+            VALUES (@timestamp, @type, @message, @scanner, @details)",
+            new { timestamp = DateTime.UtcNow.ToString("o"), type, message, scanner, details });
+    }
+
+    public async Task<IEnumerable<dynamic>> GetScannerLogs(int limit = 200, int offset = 0, string type = null, string scanner = null)
+    {
+        using var conn = CreateConnection();
+        var where = "WHERE 1=1";
+        if (!string.IsNullOrEmpty(type)) where += " AND type = @type";
+        if (!string.IsNullOrEmpty(scanner)) where += " AND scanner = @scanner";
+
+        return await conn.QueryAsync($@"
+            SELECT id, timestamp, type, message, scanner, details
+            FROM scanner_logs {where}
+            ORDER BY id DESC
+            LIMIT @limit OFFSET @offset",
+            new { limit, offset, type, scanner });
+    }
+
+    public async Task<int> GetScannerLogCount(string type = null, string scanner = null)
+    {
+        using var conn = CreateConnection();
+        var where = "WHERE 1=1";
+        if (!string.IsNullOrEmpty(type)) where += " AND type = @type";
+        if (!string.IsNullOrEmpty(scanner)) where += " AND scanner = @scanner";
+
+        return await conn.ExecuteScalarAsync<int>(
+            $"SELECT COUNT(*) FROM scanner_logs {where}",
+            new { type, scanner });
+    }
 }