Comprehensive review fixes: security, performance, code quality, and UI polish

Backend: Fix CORS wildcard+credentials, add secret key warning, remove raw
API keys from sync endpoint, fix N+1 queries in watcher/sync, fix
AttributeError on event_types, delete dead scheduled.py/templates.py,
add limit cap on history, re-validate server on URL/key update, apply
tracking/template config IDs in update_target.

HA Integration: Replace datetime.now() with dt_util.now(), fix notification
queue to only remove successfully sent items, use album UUID for entity
unique IDs, add shared links dirty flag and users cache hourly refresh,
deduplicate _is_quiet_hours, add HTTP timeouts, cache albums in config
flow, change iot_class to local_polling.

Frontend: Make i18n reactive via $state (remove window.location.reload),
add Modal transitions/a11y/Escape key, create ConfirmModal replacing all
confirm() calls, add error handling to all pages, replace Unicode nav
icons with MDI SVGs, add card hover effects, dashboard stat icons, global
focus-visible styles, form slide transitions, mobile responsive bottom
nav, fix password error color, add ~20 i18n keys (EN/RU).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

custom_components/immich_album_watcher/__init__.py

@@ -354,6 +354,7 @@ async def _send_queued_items(
 
     items = queue.get_all()
     sent_count = 0
+    sent_indices = []
     for i in indices:
         if i >= len(items):
             continue
@@ -371,14 +372,16 @@ async def _send_queued_items(
                 blocking=True,
             )
             sent_count += 1
+            sent_indices.append(i)
         except Exception:
             _LOGGER.exception("Failed to send queued notification %d", i + 1)
 
         # Small delay between notifications to avoid rate limiting
         await asyncio.sleep(1)
 
-    # Remove sent items from queue (in reverse order to preserve indices)
-    await queue.async_remove_indices(sorted(indices, reverse=True))
+    # Only remove successfully sent items (in reverse order to preserve indices)
+    if sent_indices:
+        await queue.async_remove_indices(sorted(sent_indices, reverse=True))
     _LOGGER.info("Sent %d/%d queued notifications", sent_count, len(indices))
 
 
@@ -419,7 +422,7 @@ async def _async_update_listener(
     subentries_data = entry_data["subentries"]
     for subentry_data in subentries_data.values():
         subentry_data.coordinator.update_scan_interval(new_interval)
-        subentry_data.coordinator._sync_client = sync_client
+        subentry_data.coordinator.update_sync_client(sync_client)
 
     _LOGGER.info("Updated hub options (scan_interval=%d)", new_interval)