feat: make database.Chat auditable (#24485)

Wire database.Chat into the audit system so chat lifecycle events
(creation, patches, etc.) produce audit log entries.

Part of CODAGT-200.

> 🤖

coderd/audit/diff.go

@@ -33,7 +33,8 @@ type Auditable interface {
 		idpsync.GroupSyncSettings |
 		idpsync.RoleSyncSettings |
 		database.TaskTable |
-		database.AiSeatState
+		database.AiSeatState |
+		database.Chat
 }
 
 // Map is a map of changed fields in an audited resource. It maps field names to

coderd/audit/fields.go

@@ -25,7 +25,7 @@ func BackgroundTaskFieldsBytes(ctx context.Context, logger slog.Logger, subsyste
 
 	wriBytes, err := json.Marshal(af)
 	if err != nil {
-		logger.Error(ctx, "marshal additional fields for dormancy audit", slog.Error(err))
+		logger.Error(ctx, "marshal additional fields for background audit", slog.Error(err))
 		return []byte("{}")
 	}
 

coderd/audit/request.go

@@ -134,6 +134,8 @@ func ResourceTarget[T Auditable](tgt T) string {
 		return typed.Name
 	case database.AiSeatState:
 		return "AI Seat"
+	case database.Chat:
+		return typed.Title
 	default:
 		panic(fmt.Sprintf("unknown resource %T for ResourceTarget", tgt))
 	}
@@ -200,6 +202,8 @@ func ResourceID[T Auditable](tgt T) uuid.UUID {
 		return typed.ID
 	case database.AiSeatState:
 		return typed.UserID
+	case database.Chat:
+		return typed.ID
 	default:
 		panic(fmt.Sprintf("unknown resource %T for ResourceID", tgt))
 	}
@@ -257,6 +261,8 @@ func ResourceType[T Auditable](tgt T) database.ResourceType {
 		return database.ResourceTypeTask
 	case database.AiSeatState:
 		return database.ResourceTypeAiSeat
+	case database.Chat:
+		return database.ResourceTypeChat
 	default:
 		panic(fmt.Sprintf("unknown resource %T for ResourceType", typed))
 	}
@@ -317,6 +323,10 @@ func ResourceRequiresOrgID[T Auditable]() bool {
 		return true
 	case database.AiSeatState:
 		return false
+	case database.Chat:
+		// Chats always have a non-null organization_id (since
+		// migration 000467).
+		return true
 	default:
 		panic(fmt.Sprintf("unknown resource %T for ResourceRequiresOrgID", tgt))
 	}