fix(postgres): resync id sequences so adding clients no longer collides

resetPostgresSequences hardcoded table names that did not match the models: it used "client_records" (real table is "clients") and "inbound_fallback_children" (real table is "inbound_fallbacks"). For both, pg_get_serial_sequence returned NULL, so the guarded setval was a silent no-op and those id sequences were never advanced past MAX(id) after a SQLite->Postgres migration. The first client added afterward reused an existing id and failed with duplicate key value violates unique constraint "clients_pkey".

Resolve table names from the models via GORM instead of hardcoding, and run the resync on every Postgres startup (initModels) so databases already broken by the previous migration repair themselves on boot.

database/db.go

@@ -89,6 +89,12 @@ func initModels() error {
 	if err := pruneOrphanedClientInbounds(); err != nil {
 		return err
 	}
+	if IsPostgres() {
+		if err := resyncPostgresSequences(db, models); err != nil {
+			log.Printf("Error resyncing postgres sequences: %v", err)
+			return err
+		}
+	}
 	return nil
 }