fix: Preserve corpse notoriety across server restart (#2426)

BaseCreatures are deleted on death (Mobile.OnDeath calls Delete for non-players), so after save/restart the corpse's _owner reference resolves to null. CorpseNotoriety gated its entire creature branch on `target.Owner is BaseCreature`, falling through to player-corpse logic once the reference vanished. That made monster corpses turn red (body.IsMonster -> Murderer) and innocent NPC corpses turn grey (null is not PlayerMobile -> CanBeAttacked) on the next restart.

Snapshots the relevant owner state into CorpseFlag at corpse creation: OwnerWasBaseCreature, OwnerWasSummoned, OwnerWasAnimatedDead. Folds the standalone _murderer bool into CorpseFlag.Murderer for consistency with Criminal. CorpseNotoriety now consults the flags so the creature branch stays correct without a live mobile reference.

Bumps Corpse serialization to v16 with a MigrateFrom(V15Content) that maps the old Murderer bool onto the new flag. Pre-fix corpses already on disk decay within 7 minutes; their first post-restart color may be wrong, which is acceptable.

Also documents that the schema generator must be run after every version bump (`dotnet tool run ModernUOSchemaGenerator -- ModernUO.slnx`) since `dotnet build` does not emit migration JSON files.

Projects/UOContent/Migrations/Server.Items.Corpse.v16.json

@@ -0,0 +1,123 @@
+{
+  "version": 16,
+  "type": "Server.Items.Corpse",
+  "properties": [
+    {
+      "name": "RestoreEquip",
+      "type": "System.Collections.Generic.List\u003CServer.Item\u003E",
+      "rule": "ListMigrationRule",
+      "ruleArguments": [
+        "Server.Item",
+        "SerializableInterfaceMigrationRule"
+      ]
+    },
+    {
+      "name": "Flags",
+      "type": "Server.Items.CorpseFlag",
+      "rule": "EnumMigrationRule"
+    },
+    {
+      "name": "TimeOfDeath",
+      "type": "System.DateTime",
+      "rule": "PrimitiveTypeMigrationRule",
+      "ruleArguments": [
+        "DeltaTime"
+      ]
+    },
+    {
+      "name": "RestoreTable",
+      "type": "System.Collections.Generic.Dictionary\u003CServer.Item, Server.Point3D\u003E",
+      "rule": "DictionaryMigrationRule",
+      "ruleArguments": [
+        "Server.Item",
+        "SerializableInterfaceMigrationRule",
+        "0",
+        "Server.Point3D",
+        "PrimitiveUOTypeMigrationRule",
+        "1",
+        "Point3D"
+      ]
+    },
+    {
+      "name": "DecayTimer",
+      "type": "Server.Timer",
+      "rule": "TimerMigrationRule",
+      "ruleArguments": [
+        "@TimerDrift"
+      ]
+    },
+    {
+      "name": "Looters",
+      "type": "System.Collections.Generic.HashSet\u003CServer.Mobile\u003E",
+      "rule": "HashSetMigrationRule",
+      "ruleArguments": [
+        "Server.Mobile",
+        "SerializableInterfaceMigrationRule"
+      ]
+    },
+    {
+      "name": "Killer",
+      "type": "Server.Mobile",
+      "rule": "SerializableInterfaceMigrationRule"
+    },
+    {
+      "name": "Aggressors",
+      "type": "System.Collections.Generic.List\u003CServer.Mobile\u003E",
+      "rule": "ListMigrationRule",
+      "ruleArguments": [
+        "Server.Mobile",
+        "SerializableInterfaceMigrationRule"
+      ]
+    },
+    {
+      "name": "Owner",
+      "type": "Server.Mobile",
+      "rule": "SerializableInterfaceMigrationRule"
+    },
+    {
+      "name": "CorpseName",
+      "type": "string",
+      "rule": "PrimitiveTypeMigrationRule",
+      "ruleArguments": [
+        ""
+      ]
+    },
+    {
+      "name": "AccessLevel",
+      "type": "Server.AccessLevel",
+      "rule": "EnumMigrationRule"
+    },
+    {
+      "name": "Guild",
+      "type": "Server.Guilds.Guild",
+      "rule": "SerializableInterfaceMigrationRule"
+    },
+    {
+      "name": "EquipItems",
+      "type": "System.Collections.Generic.List\u003CServer.Item\u003E",
+      "rule": "ListMigrationRule",
+      "ruleArguments": [
+        "Server.Item",
+        "SerializableInterfaceMigrationRule"
+      ]
+    },
+    {
+      "name": "Hair",
+      "type": "Server.VirtualHairInfo",
+      "rule": "RawSerializableMigrationRule",
+      "ruleArguments": [
+        "",
+        "@CanBeNull"
+      ]
+    },
+    {
+      "name": "FacialHair",
+      "type": "Server.VirtualHairInfo",
+      "rule": "RawSerializableMigrationRule",
+      "ruleArguments": [
+        "",
+        "@CanBeNull"
+      ]
+    }
+  ]
+}