feat: stack glob patterns and route severity levels (#1651)

* feat: add stack glob patterns and route severity levels

Operators can filter notification routes and mute rules with anchored * globs, and routes can target info, warning, or error. Matching is fail-closed for unsafe stored patterns; write paths keep partial-PUT semantics and ReDoS caps.

* test: split mute and routing chip tests to avoid dialog race

* fix: move stack pattern client validator out of PatternChips

* fix: bound stack glob matching and atomic pattern chip saves

backend/src/__tests__/notification-apprise.test.ts

@@ -69,6 +69,7 @@ function makeAppriseRoute(overrides: Record<string, unknown> = {}) {
     stack_patterns: ['my-app'],
     label_ids: null,
     categories: null,
+    levels: null,
     channel_type: 'apprise' as const,
     channel_url: KEYED,
     config: '{}',