fix: replace alert() access guard in event settings with proper UX

- Remove blocking alert() + module-level browser guard
- Move access check to onMount with 500ms grace delay (matches /core pattern)
- Add {:else} block: Lock icon + 'Access Restricted' message + redirect link
- Remove now-unused 'browser' import; add Lock from lucide

documentation/PROJECT__AE_Access_Control_UX.md

@@ -1,8 +1,9 @@
 # PROJECT: Access Control UX — Session Expired & Access Denied
 
-**Status:** Planning
+**Status:** In Progress
 **Priority:** Medium-High
 **Created:** 2026-02
+**Updated:** 2026-03-11
 **Related:** `src/routes/+layout.svelte`, `src/lib/ae_api/`, `src/lib/stores/ae_stores.ts`
 
 ---
@@ -175,7 +176,7 @@ The settings page check should mirror the `/core` pattern:
 
 ## 5. Implementation Plan
 
-### Step 1: Add `ae_auth_error` store
+### Step 1: Add `ae_auth_error` store ✅ DONE (2026-03-11)
 
 **File:** `src/lib/stores/ae_stores.ts`
 
@@ -187,7 +188,7 @@ export const ae_auth_error = writable<{ type: 'expired' | null, ts: number | nul
 
 ---
 
-### Step 2: Wire API helpers to `ae_auth_error`
+### Step 2: Wire API helpers to `ae_auth_error` ✅ DONE (2026-03-11)
 
 **Files:** `src/lib/ae_api/api_get_object.ts`, `api_post_object.ts`, `api_patch_object.ts` (same pattern in all three)
 
@@ -202,7 +203,7 @@ ae_auth_error.set({ type: 'expired', ts: Date.now() });
 
 ---
 
-### Step 3: Wire `flag_expired` in root layout
+### Step 3: Wire `flag_expired` in root layout ✅ DONE (2026-03-11)
 
 **File:** `src/routes/+layout.svelte`
 
@@ -230,7 +231,7 @@ Add the dismissible banner to the template (after/near the existing `is_offline`
 
 ---
 
-### Step 4: Create `element_access_denied.svelte`
+### Step 4: Create `element_access_denied.svelte` ⬅ NEXT
 
 **File:** `src/lib/elements/element_access_denied.svelte`
 
@@ -238,7 +239,7 @@ Reusable card for inline access denial. Props per design decision 4c.
 
 ---
 
-### Step 5: Fix Event Settings `alert()`
+### Step 5: Fix Event Settings `alert()` ⬅ NEXT
 
 **File:** `src/routes/events/[event_id]/settings/+page.svelte`