feat: NUT (Network UPS Tools) service provider + provider-agnostic UI

Add full NUT support as a polling-based service provider:
- Async TCP client for upsd protocol (port 3493, configurable)
- 8 event types: online, on_battery, low_battery, battery_restored,
  comms_lost, comms_restored, replace_battery, overload
- 3 bot commands: /status, /devices, /battery
- 38 Jinja2 templates (EN+RU notification + command templates)
- Database: tracking config fields, migration, seeds
- Frontend: provider form with host/port/credentials, grid items, i18n

Provider-agnostic UI improvements:
- Remove hardcoded 'immich' defaults from all config forms
- Dynamic collection labels per provider type (Albums/Repos/Boards/UPS Devices)
- Capability-driven test types instead of provider type checks
- Template variable helpers for all providers (was Immich-only)
- Guard Immich-only shared link check to Immich providers
- Auto-clear stale global provider filter from localStorage
- EntitySelect search placeholder shows current selection
- Fix noneLabel in linked target config selectors

New CLAUDE.md rule #8: no provider-specific hardcoding

frontend/src/lib/components/EntitySelect.svelte

@@ -130,7 +130,7 @@
 			<input
 				bind:this={inputEl}
 				bind:value={query}
-				placeholder={placeholder}
+				placeholder={selected ? selected.label : placeholder}
 				class="ep-input"
 				type="text"
 				autocomplete="off"

frontend/src/lib/grid-items.ts

@@ -12,6 +12,7 @@ const PROVIDER_TYPE_ICONS: Record<string, string> = {
 	gitea: 'mdiGit',
 	planka: 'mdiViewDashboard',
 	scheduler: 'mdiClockOutline',
+	nut: 'mdiBatteryCharging80',
 };
 
 /** Get the default icon for a provider, falling back by type then generic. */
@@ -118,6 +119,7 @@ export const providerTypeFilterItems = (): GridItem[] => [
 	{ value: 'gitea', icon: 'mdiGit', label: t('providers.typeGitea'), desc: t('gridDesc.providerGitea') },
 	{ value: 'planka', icon: 'mdiViewDashboard', label: t('providers.typePlanka'), desc: t('gridDesc.providerPlanka') },
 	{ value: 'scheduler', icon: 'mdiClockOutline', label: t('providers.typeScheduler'), desc: t('gridDesc.providerScheduler') },
+	{ value: 'nut', icon: PROVIDER_TYPE_ICONS.nut, label: t('providers.typeNut'), desc: t('gridDesc.providerNut') },
 ];
 
 // --- Provider type ---
@@ -127,4 +129,5 @@ export const providerTypeItems = (): GridItem[] => [
 	{ value: 'gitea', icon: PROVIDER_TYPE_ICONS.gitea, label: t('providers.typeGitea'), desc: t('gridDesc.providerGitea') },
 	{ value: 'planka', icon: PROVIDER_TYPE_ICONS.planka, label: t('providers.typePlanka'), desc: t('gridDesc.providerPlanka') },
 	{ value: 'scheduler', icon: PROVIDER_TYPE_ICONS.scheduler, label: t('providers.typeScheduler'), desc: t('gridDesc.providerScheduler') },
+	{ value: 'nut', icon: PROVIDER_TYPE_ICONS.nut, label: t('providers.typeNut'), desc: t('gridDesc.providerNut') },
 ];

frontend/src/lib/i18n/en.json

@@ -111,6 +111,7 @@
 		"typeGitea": "Gitea",
 		"typePlanka": "Planka",
 		"typeScheduler": "Scheduler",
+		"typeNut": "NUT (UPS)",
 		"loadError": "Failed to load providers.",
 		"externalDomain": "External Domain",
 		"optional": "optional",
@@ -127,6 +128,13 @@
 		"apiTokenHint": "Optional. Needed for connection testing and repository listing.",
 		"webhookUrl": "Webhook URL",
 		"webhookUrlHint": "Set this as the Target URL in Gitea webhook settings (relative to your bridge host).",
+		"nutHost": "NUT Server Host",
+		"nutHostPlaceholder": "192.168.1.100 or ups.local",
+		"nutPort": "NUT Server Port",
+		"nutUsername": "Username",
+		"nutPassword": "Password",
+		"nutUsernameHint": "Optional — only needed if upsd requires authentication",
+		"nutPasswordHint": "Optional — upsd user password",
 		"testAndSave": "Test & Save",
 		"saveWithoutTest": "Save without testing"
 	},
@@ -141,6 +149,12 @@
 		"selectServer": "Select provider...",
 		"albums": "Albums",
 		"selectAlbums": "Select albums...",
+		"repositories": "Repositories",
+		"selectRepositories": "Select repositories...",
+		"boards": "Boards",
+		"selectBoards": "Select boards...",
+		"upsDevices": "UPS Devices",
+		"selectUpsDevices": "Select UPS devices...",
 		"eventTypes": "Event Types",
 		"notificationTargets": "Notification Targets",
 		"scanInterval": "Scan Interval (seconds)",
@@ -826,7 +840,8 @@
 		"providerImmich": "Self-hosted photo server",
 		"providerGitea": "Self-hosted Git service",
 		"providerPlanka": "Self-hosted Kanban board",
-		"providerScheduler": "Time-based scheduled messages"
+		"providerScheduler": "Time-based scheduled messages",
+		"providerNut": "Network UPS monitoring"
 	},
 	"error": {
 		"notFound": "Page not found",

frontend/src/lib/i18n/ru.json

@@ -111,6 +111,7 @@
 		"typeGitea": "Gitea",
 		"typePlanka": "Planka",
 		"typeScheduler": "Планировщик",
+		"typeNut": "NUT (ИБП)",
 		"loadError": "Не удалось загрузить провайдеры.",
 		"externalDomain": "Внешний домен",
 		"optional": "необязательно",
@@ -127,6 +128,13 @@
 		"apiTokenHint": "Необязательно. Нужен для проверки подключения и получения списка репозиториев.",
 		"webhookUrl": "URL вебхука",
 		"webhookUrlHint": "Укажите этот URL в настройках вебхука Gitea (относительно хоста bridge).",
+		"nutHost": "Хост NUT-сервера",
+		"nutHostPlaceholder": "192.168.1.100 или ups.local",
+		"nutPort": "Порт NUT-сервера",
+		"nutUsername": "Имя пользователя",
+		"nutPassword": "Пароль",
+		"nutUsernameHint": "Необязательно — только если upsd требует аутентификации",
+		"nutPasswordHint": "Необязательно — пароль пользователя upsd",
 		"testAndSave": "Проверить и сохранить",
 		"saveWithoutTest": "Сохранить без проверки"
 	},
@@ -141,6 +149,12 @@
 		"selectServer": "Выберите провайдер...",
 		"albums": "Альбомы",
 		"selectAlbums": "Выберите альбомы...",
+		"repositories": "Репозитории",
+		"selectRepositories": "Выберите репозитории...",
+		"boards": "Доски",
+		"selectBoards": "Выберите доски...",
+		"upsDevices": "ИБП устройства",
+		"selectUpsDevices": "Выберите ИБП...",
 		"eventTypes": "Типы событий",
 		"notificationTargets": "Получатели уведомлений",
 		"scanInterval": "Интервал проверки (секунды)",
@@ -826,7 +840,8 @@
 		"providerImmich": "Фотосервер для самостоятельного размещения",
 		"providerGitea": "Git-сервер для самостоятельного размещения",
 		"providerPlanka": "Канбан-доска для самостоятельного размещения",
-		"providerScheduler": "Запланированные сообщения по расписанию"
+		"providerScheduler": "Запланированные сообщения по расписанию",
+		"providerNut": "Мониторинг ИБП через NUT"
 	},
 	"error": {
 		"notFound": "Страница не найдена",

frontend/src/lib/stores/provider-filter.svelte.ts

@@ -26,7 +26,15 @@ function loadFromStorage(): void {
 loadFromStorage();
 
 export const globalProviderFilter = {
-	get id() { return _providerId; },
+	get id() {
+		// If providers are loaded and the stored ID doesn't match any, auto-clear
+		if (_providerId != null && providersCache.items.length > 0 &&
+			!providersCache.items.some(p => p.id === _providerId)) {
+			globalProviderFilter.clear();
+			return null;
+		}
+		return _providerId;
+	},
 	get initialized() { return _initialized; },
 
 	set(id: number | null) {
@@ -46,8 +54,9 @@ export const globalProviderFilter = {
 
 	/** The currently selected provider object (reactive). */
 	get provider() {
-		if (_providerId == null) return null;
-		return providersCache.items.find(p => p.id === _providerId) ?? null;
+		const id = this.id; // triggers stale-ID auto-clear
+		if (id == null) return null;
+		return providersCache.items.find(p => p.id === id) ?? null;
 	},
 
 	/** The provider type string, or null. */