feat: introduce index layout skill for FULL_PAGE index/list tables

- Added a new skill for managing index and list table layouts in the ERP project, detailing layout and data contracts.
- Updated project guidelines to reference the new index layout skill.
- Introduced rules for page composition, column definitions, audit fields, action column width, and toolbar functionality.
- Created utility functions for computing action column width and formatting audit fields, along with corresponding unit tests to ensure reliability.

These changes enhance the application by providing a structured approach to index layouts, improving consistency and usability across the ERP project.

packages/ui/src/foundations/enterprise-module/components/data-table/audit-column.utils.ts

@@ -0,0 +1,33 @@
+import { DateUtils } from '@repo/utils';
+
+export const EMPTY_AUDIT_DISPLAY = '-';
+
+const AUDIT_TIMESTAMP_FORMAT = 'DD-MM-YYYY, HH:mm';
+
+export function resolveAuditValue(
+  row: Record<string, unknown> | null | undefined,
+  camelKey: string,
+  snakeKey: string,
+): unknown {
+  if (!row) return undefined;
+  const camelValue = row[camelKey];
+  if (camelValue !== undefined && camelValue !== null) return camelValue;
+  return row[snakeKey];
+}
+
+export function formatAuditActor(value: unknown): string {
+  if (value === undefined || value === null || value === '') return EMPTY_AUDIT_DISPLAY;
+  if (typeof value === 'string') return value;
+  if (typeof value === 'object') {
+    const actor = value as { username?: unknown; name?: unknown; id?: unknown };
+    const label = actor.username ?? actor.name ?? actor.id;
+    if (label === undefined || label === null || label === '') return EMPTY_AUDIT_DISPLAY;
+    return String(label);
+  }
+  return String(value);
+}
+
+export function formatAuditTimestamp(value: unknown): string {
+  if (value === undefined || value === null || value === '') return EMPTY_AUDIT_DISPLAY;
+  return new DateUtils(Number(value)).format(AUDIT_TIMESTAMP_FORMAT);
+}