Docs: preview start_date defaults to the household-local today

The occurrence-preview request docstring and the admin client's
startDate comment still said the default is the API host's today. The
route defaults to the household-local today in the configured
timezone, and uses the host's local time only when that setting is empty.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

admin/src/api/definitions.ts

@@ -150,7 +150,10 @@ export async function updateDefinition(
 export const OCCURRENCES_PREVIEW_PATH = `${DEFINITIONS_PATH}/occurrences-preview`;
 
 export interface OccurrencesPreviewOptions {
-  /** "YYYY-MM-DD"; the API defaults to its host's today. */
+  /**
+   * "YYYY-MM-DD"; the API defaults to the household-local today in the
+   * configured `timezone` (the API host's local time when that is empty).
+   */
   startDate?: string;
   /** 1..50; the API defaults to 10. */
   count?: number;

api/routes_admin.py

@@ -536,9 +536,10 @@ class AdminOccurrencesPreviewRequest(BaseModel):
 
     ``rule`` is the SAME object create/edit take.  ``start_date`` is an
     optional strict ``YYYY-MM-DD`` (validated by the core; default the
-    API host's today).  ``count`` is a strict JSON integer in
-    1..``_PREVIEW_MAX_COUNT`` — anything else is 422 before any handler
-    code runs.
+    household-local today in the configured ``timezone``, empty falling
+    back to the API host's local time).  ``count`` is a strict JSON
+    integer in 1..``_PREVIEW_MAX_COUNT`` — anything else is 422 before
+    any handler code runs.
     """
 
     rule: AdminRuleRequest