Fix collection health overflow and query stats DOP type mismatch

- collection_health view: cast duration_ms and rows_collected to bigint
  before AVG/SUM to prevent arithmetic overflow after 7 days of data
- collection_health C# reader: use Convert.ToInt64 for avg_duration_ms,
  update model property from int to long
- query_stats reader: min_dop/max_dop columns are bigint in the table
  but reader called GetInt16() — changed to Convert.ToInt16(GetValue())

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata

Dashboard/Models/CollectionHealthItem.cs

@@ -19,7 +19,7 @@ public class CollectionHealthItem
         public decimal FailureRatePercent { get; set; }
         public long TotalRuns7d { get; set; }
         public long FailedRuns7d { get; set; }
-        public int AvgDurationMs { get; set; }
+        public long AvgDurationMs { get; set; }
         public long TotalRowsCollected7d { get; set; }
     }
 }

Dashboard/Services/DatabaseService.QueryPerformance.cs

@@ -1014,8 +1014,8 @@ USE HINT('ENABLE_PARALLEL_PLAN_PREFERENCE')
                             AvgRows = reader.IsDBNull(24) ? null : reader.GetInt64(24),
                             MinRows = reader.IsDBNull(25) ? null : reader.GetInt64(25),
                             MaxRows = reader.IsDBNull(26) ? null : reader.GetInt64(26),
-                            MinDop = reader.IsDBNull(27) ? null : reader.GetInt16(27),
-                            MaxDop = reader.IsDBNull(28) ? null : reader.GetInt16(28),
+                            MinDop = reader.IsDBNull(27) ? null : Convert.ToInt16(reader.GetValue(27)),
+                            MaxDop = reader.IsDBNull(28) ? null : Convert.ToInt16(reader.GetValue(28)),
                             MinGrantKb = reader.IsDBNull(29) ? null : reader.GetInt64(29),
                             MaxGrantKb = reader.IsDBNull(30) ? null : reader.GetInt64(30),
                             TotalSpills = reader.IsDBNull(31) ? 0 : reader.GetInt64(31),

Dashboard/Services/DatabaseService.cs

@@ -176,7 +176,7 @@ CASE health_status
                         FailureRatePercent = reader.IsDBNull(4) ? 0m : Convert.ToDecimal(reader.GetValue(4), CultureInfo.InvariantCulture),
                         TotalRuns7d = reader.IsDBNull(5) ? 0L : Convert.ToInt64(reader.GetValue(5), CultureInfo.InvariantCulture),
                         FailedRuns7d = reader.IsDBNull(6) ? 0L : Convert.ToInt64(reader.GetValue(6), CultureInfo.InvariantCulture),
-                        AvgDurationMs = reader.IsDBNull(7) ? 0 : Convert.ToInt32(reader.GetValue(7), CultureInfo.InvariantCulture),
+                        AvgDurationMs = reader.IsDBNull(7) ? 0 : Convert.ToInt64(reader.GetValue(7), CultureInfo.InvariantCulture),
                         TotalRowsCollected7d = reader.IsDBNull(8) ? 0L : Convert.ToInt64(reader.GetValue(8), CultureInfo.InvariantCulture)
                     });
                 }

install/47_create_reporting_views.sql

@@ -69,7 +69,7 @@ WITH
             (
                 CASE
                     WHEN cl.collection_status = N'SUCCESS'
-                    THEN cl.duration_ms
+                    THEN CAST(cl.duration_ms AS bigint)
                     ELSE NULL
                 END
             ),
@@ -78,8 +78,8 @@ WITH
             (
                 CASE
                     WHEN cl.collection_status = N'SUCCESS'
-                    THEN cl.rows_collected
-                    ELSE 0
+                    THEN CAST(cl.rows_collected AS bigint)
+                    ELSE CAST(0 AS bigint)
                 END
             )
     FROM config.collection_log AS cl
@@ -157,7 +157,7 @@ SELECT
         ),
     total_runs_7d = cs.total_runs,
     failed_runs_7d = cs.failed_runs,
-    avg_duration_ms = CONVERT(integer, cs.avg_duration_ms),
+    avg_duration_ms = CONVERT(bigint, cs.avg_duration_ms),
     total_rows_collected_7d = cs.total_rows_collected
 FROM collector_stats AS cs
 LEFT JOIN recent_failures AS rf