feat(backup): replace JSON import/export with SQLite database backup system

Replace the JSON-based import/export with a proper backup system that copies
the SQLite database file directly. Supports manual on-demand backups, periodic
scheduled backups via node-cron, configurable retention, file download, and
full database restore.

- Add backupService with VACUUM INTO for safe DB copies
- Add backupScheduler following healthcheckScheduler pattern
- Add 6 admin API endpoints (create, list, download, restore, delete, schedule)
- Add BackupPanel UI with backup table, confirmation dialogs, schedule config
- Add backup fields to SystemSettings schema
- Remove old ImportExportPanel, exportService, importService, and related code

src/lib/utils/validators.ts

@@ -220,69 +220,12 @@ export const createPermissionSchema = z.object({
 	level: z.enum([PermissionLevel.VIEW, PermissionLevel.EDIT, PermissionLevel.ADMIN])
 });
 
-// --- Import/Export ---
+// --- Backup Schedule ---
 
-const importAppSchema = z.object({
-	name: z.string().min(1).max(200),
-	url: z.string().url(),
-	icon: z.string().max(500).nullable(),
-	iconType: z.string().max(50),
-	description: z.string().max(1000).nullable(),
-	category: z.string().max(100).nullable(),
-	tags: z.string().max(500),
-	healthcheckEnabled: z.boolean(),
-	healthcheckInterval: z.number().int().min(30).max(86400),
-	healthcheckMethod: z.string(),
-	healthcheckExpectedStatus: z.number().int().min(100).max(599),
-	healthcheckTimeout: z.number().int().min(1000).max(30000)
-});
-
-const importWidgetSchema = z.object({
-	type: z.string().min(1),
-	order: z.number().int().min(0),
-	config: z.string(),
-	appName: z.string().nullable()
-});
-
-const importSectionSchema = z.object({
-	title: z.string().min(1).max(200),
-	icon: z.string().max(500).nullable(),
-	order: z.number().int().min(0),
-	isExpandedByDefault: z.boolean(),
-	widgets: z.array(importWidgetSchema)
-});
-
-const importBoardSchema = z.object({
-	name: z.string().min(1).max(200),
-	icon: z.string().max(500).nullable(),
-	description: z.string().max(1000).nullable(),
-	isDefault: z.boolean(),
-	isGuestAccessible: z.boolean(),
-	backgroundConfig: z.string().nullable(),
-	sections: z.array(importSectionSchema)
-});
-
-const importGroupSchema = z.object({
-	name: z.string().min(1).max(100),
-	description: z.string().max(500).nullable(),
-	isDefault: z.boolean()
-});
-
-const importSettingsSchema = z.object({
-	authMode: z.string().optional(),
-	registrationEnabled: z.boolean().optional(),
-	defaultTheme: z.string().optional(),
-	defaultPrimaryColor: z.string().optional(),
-	healthcheckDefaults: z.string().optional()
-});
-
-export const importDataSchema = z.object({
-	version: z.string(),
-	exportedAt: z.string(),
-	apps: z.array(importAppSchema).max(1000),
-	boards: z.array(importBoardSchema).max(100),
-	groups: z.array(importGroupSchema).max(100),
-	settings: importSettingsSchema
+export const updateBackupScheduleSchema = z.object({
+	backupEnabled: z.boolean().optional(),
+	backupCronExpression: z.string().min(1).max(100).optional(),
+	backupMaxCount: z.number().int().min(1).max(100).optional()
 });
 
 // --- System Settings ---
@@ -468,7 +411,10 @@ export const auditLogQuerySchema = z.object({
 			AuditAction.APP_DELETED,
 			AuditAction.SETTINGS_UPDATED,
 			AuditAction.IMPORT,
-			AuditAction.EXPORT
+			AuditAction.EXPORT,
+			AuditAction.BACKUP_CREATED,
+			AuditAction.BACKUP_RESTORED,
+			AuditAction.BACKUP_DELETED
 		])
 		.optional(),
 	entityType: z.string().max(50).optional(),