fix: normalize local postgres date columns

frontend/src/lib/db/local-postgres-client-core.ts

@@ -128,6 +128,16 @@ function databaseValue(type: string | undefined, value: unknown): unknown {
   return value;
 }
 
+function queryValue(type: string | undefined, value: unknown): unknown {
+  if (type !== "date" || !(value instanceof Date)) return value;
+  // pg parses DATE at local midnight; UTC formatting can shift the calendar day.
+  return [
+    String(value.getFullYear()).padStart(4, "0"),
+    String(value.getMonth() + 1).padStart(2, "0"),
+    String(value.getDate()).padStart(2, "0"),
+  ].join("-");
+}
+
 class LocalPostgresQueryBuilder implements PromiseLike<QueryResult> {
   private selectedColumns: string[] | null = null;
   private mutation: Mutation | null = null;
@@ -411,7 +421,14 @@ class LocalPostgresQueryBuilder implements PromiseLike<QueryResult> {
           }
 
           const result = await client.query(sql, parameters);
-          const rows = result.rows;
+          const rows = result.rows.map((row) =>
+            Object.fromEntries(
+              Object.entries(row).map(([column, value]) => [
+                column,
+                queryValue(types.get(column), value),
+              ]),
+            ),
+          );
           let data: unknown = this.selectedColumns ? rows : null;
           if (this.cardinality !== "many") {
             if (