feat: production hardening + password reset, metrics, signed webhooks

Security hardening (CRITICAL/HIGH from production-readiness audit):
- Require strong JWT_SECRET + separate INTEGRATION_ENCRYPTION_KEY at boot;
  refuse placeholder defaults. Integration key now derived via HKDF.
- SSRF guard (src/lib/server/utils/safeFetch.ts): DNS-resolves and rejects
  RFC1918/loopback/link-local/IPv4-mapped IPv6/decimal-IP/cloud-metadata.
  Manual redirect handling re-validates each 3xx Location hop. Applied to
  healthcheck, RSS, calendar, metric, system-stats, camera, notifications,
  discovery, apps/preview, and all integration clients.
- API tokens, session refresh tokens, invite tokens, password-reset tokens
  switched from bcrypt to sha256 with @unique indexed lookup (O(1) instead
  of O(N) bcrypt-compares; eliminates a trivial DoS).
- Refresh-token reuse detection via Session.previousTokenHash.
- Permission checks on App PATCH/DELETE and Widget/Section endpoints.
- /api/integrations/alerts now requires auth.
- SVG uploads sanitized through DOMPurify (svg profile, scheme allow-list).
- Custom CSS sanitizer + selector scoping (decodes CSS unicode escapes
  before pattern match, drops forbidden at-rules incl. @import without
  whitespace, strips dangerous url() args). Scoped to .custom-css-scope.
- Backup restore validates SQLite magic header, takes a safety snapshot,
  uses atomic rename, re-applies pragmas.
- SQLite WAL + busy_timeout + foreign_keys + synchronous=NORMAL at startup.
- Healthcheck scheduler was dead code; wired in hooks.server.ts with
  HMR-safe singleton, concurrency cap, overlap prevention, retention jobs
  for AppClick/Notification/AuditLog. Composite indexes added on hot paths.
- Security headers (CSP, HSTS-on-https, X-Frame-Options, Permissions-Policy)
  emitted on every response.
- Account-enumeration mitigation on login (dummy bcrypt on no-user/oauth
  branches) + rate limiting on login/register/onboarding/refresh/invite/
  password-reset.
- OAuth callback sanitizes IdP error_description before echoing.

New features:
- Custom +error.svelte pages (root + boards + admin) via shared
  ErrorState component. Inverted hierarchy (status as label, title as hero).
- /forgot-password + /reset-password + admin-mediated /admin/password-resets
  page. SHA256 tokens, 24h TTL, all sessions revoked on apply.
- /invite page for manual invite-token redemption.
- /api/metrics Prometheus exposition with optional METRICS_TOKEN bearer
  auth. Counters for login/healthcheck/notification/integration; gauges
  for users/boards/apps + per-status app counts.
- Webhook HMAC-SHA256 signing for HTTP notification channels (optional
  shared secret + configurable signature header, default X-Signature-256).
- PATCH /api/users/me/password for self-service password change.
- Persistent uploads at /app/data/uploads with served-from-volume handler
  at /uploads/[...path]. SVGs served with CSP: sandbox.
- /api/health does a DB ping; returns 503 on disconnect.
- Public /status filtered to guest-accessible-board apps when unauthenticated.
- Audit log coverage: LOGIN_SUCCESS/FAILED, LOGOUT, OAUTH_LOGIN,
  OAUTH_USER_PROVISIONED, SESSION_REVOKED, API_TOKEN_*, INVITE_*,
  APP_UPDATED, PASSWORD_CHANGED, PASSWORD_RESET_*.

Performance:
- Board page: removed double findAll() over-fetch; include links + appTags
  in board query; widgets lazy-loaded via dynamic imports (marked,
  DOMPurify, hls.js, integration renderers).
- uptimeService.getAllAppsUptime: single batched query instead of N+1.
- 30s in-memory user-locals cache; invalidated on user mutation.
- pruneOldStatuses: single window-function DELETE instead of N+1.

Code quality:
- Typed error classes (NotFoundError, PermissionError, RateLimitError,
  IntegrationError) with toHttpError mapper.
- Locals.user shape exposes avatarUrl and narrows role via guard.
- App input types derived from Zod schemas via z.infer.
- 274 tests passing (up from 212); 62 new tests covering SSRF guard,
  CSS sanitizer, SVG sanitizer, rate limiter.

CI / Docker / config:
- Test workflow adds build, docker-build, audit jobs. Release workflow
  uses buildx multi-arch (amd64+arm64) with provenance + SBOM.
- Dockerfile uses tini, multi-stage prune, persistent uploads dir, single
  prisma migrate deploy (no destructive db push fallback).
- docker-compose: JWT_SECRET + INTEGRATION_ENCRYPTION_KEY required at
  startup, log rotation, resource limits.
- README documents breaking-change upgrade path.

Bug fixes from UI/UX review:
- ~55 missing i18n keys added to en/ru (auth flows, error pages, admin
  nav, register invite banner, settings.card_style).
- Hardcoded English on login replaced with $t('auth.remember_me').
- Admin nav uses i18n keys; mobile horizontal-scroll layout.
- Page <title> tags standardized.
- Password-resets: separated error/info/success surfaces, ConfirmDialog
  replaces window.confirm.
- Auth pages have matching lucide icon badges.
- Webhook secret has eye toggle and monospace input.
- text-green-500 → text-emerald-500 to match codebase convention.

Pre-existing CI lint failures cleaned up (31 errors → 0): each-key
attributes added, unused-svelte-ignore comments removed, two any casts
typed, dead skeleton components removed, /boards/[id]/edit redirect to
inline edit mode.

Tests: 274 / 274 passing
Type check: 0 errors / 0 warnings
Build: green

src/lib/server/services/__tests__/discoveryService.test.ts

@@ -103,6 +103,27 @@ describe('discoveryService', () => {
 	});
 
 	describe('discoverTraefik', () => {
+		// Build a Response-like object compatible with both raw fetch tests and
+		// the SafeResponse wrapper used by safeFetch.
+		function mockResponse(body: unknown, ok: boolean, status: number) {
+			const bodyString = JSON.stringify(body);
+			const bodyBytes = new TextEncoder().encode(bodyString);
+			const stream = new ReadableStream<Uint8Array>({
+				start(controller) {
+					controller.enqueue(bodyBytes);
+					controller.close();
+				}
+			});
+			return {
+				ok,
+				status,
+				headers: new Headers({ 'content-type': 'application/json' }),
+				body: stream,
+				json: () => Promise.resolve(body),
+				text: () => Promise.resolve(bodyString)
+			};
+		}
+
 		it('returns services from Traefik routers', async () => {
 			const routers = [
 				{
@@ -123,15 +144,9 @@ describe('discoveryService', () => {
 				'fetch',
 				vi.fn((url: string) => {
 					if (url.includes('/api/http/routers')) {
-						return Promise.resolve({
-							ok: true,
-							json: () => Promise.resolve(routers)
-						});
+						return Promise.resolve(mockResponse(routers, true, 200));
 					}
-					return Promise.resolve({
-						ok: true,
-						json: () => Promise.resolve(services)
-					});
+					return Promise.resolve(mockResponse(services, true, 200));
 				})
 			);
 
@@ -148,7 +163,7 @@ describe('discoveryService', () => {
 		it('returns error on Traefik API failure', async () => {
 			vi.stubGlobal(
 				'fetch',
-				vi.fn(() => Promise.resolve({ ok: false, status: 500 }))
+				vi.fn(() => Promise.resolve(mockResponse({}, false, 500)))
 			);
 
 			const result = await discoverTraefik('http://traefik.local:8080');