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>

frontend/src/lib/i18n/en.json

@@ -53,7 +53,11 @@
 		"connecting": "Connecting...",
 		"noServers": "No servers configured yet.",
 		"delete": "Delete",
-		"confirmDelete": "Delete this server?"
+		"confirmDelete": "Delete this server?",
+		"online": "Online",
+		"offline": "Offline",
+		"checking": "Checking...",
+		"loadError": "Failed to load servers."
 	},
 	"trackers": {
 		"title": "Trackers",
@@ -177,7 +181,8 @@
 		"private": "Private",
 		"group": "Group",
 		"supergroup": "Supergroup",
-		"channel": "Channel"
+		"channel": "Channel",
+		"confirmDelete": "Delete this bot?"
 	},
 	"trackingConfig": {
 		"title": "Tracking Configs",
@@ -211,7 +216,20 @@
 		"assetType": "Asset type",
 		"minRating": "Min rating",
 		"memoryMode": "Memory Mode (On This Day)",
-		"test": "Test"
+		"test": "Test",
+		"confirmDelete": "Delete this tracking config?",
+		"sortNone": "None",
+		"sortDate": "Date",
+		"sortRating": "Rating",
+		"sortName": "Name",
+		"orderDesc": "Descending",
+		"orderAsc": "Ascending",
+		"albumModePerAlbum": "Per album",
+		"albumModeCombined": "Combined",
+		"albumModeRandom": "Random",
+		"assetTypeAll": "All",
+		"assetTypePhoto": "Photo",
+		"assetTypeVideo": "Video"
 	},
 	"templateConfig": {
 		"title": "Template Configs",
@@ -246,7 +264,8 @@
 		"memoryMode": "Memory mode",
 		"telegramSettings": "Telegram",
 		"videoWarning": "Video warning",
-		"preview": "Preview"
+		"preview": "Preview",
+		"confirmDelete": "Delete this template config?"
 	},
 	"common": {
 		"loading": "Loading...",
@@ -258,6 +277,10 @@
 		"confirm": "Confirm",
 		"error": "Error",
 		"success": "Success",
+		"none": "None",
+		"noneDefault": "None (default)",
+		"loadError": "Failed to load data",
+		"headersInvalid": "Invalid JSON",
 		"language": "Language",
 		"theme": "Theme",
 		"light": "Light",
@@ -268,6 +291,8 @@
 		"changePassword": "Change Password",
 		"currentPassword": "Current password",
 		"newPassword": "New password",
-		"passwordChanged": "Password changed successfully"
+		"passwordChanged": "Password changed successfully",
+		"expand": "Expand",
+		"collapse": "Collapse"
 	}
 }