fix(ui/alerts): align RouteMetric metric enum with backend; pre-populate ROUTE_METRIC defaults

- RouteMetricForm dropped P95_LATENCY_MS — not in cameleer-server-core
  RouteMetric enum (valid: ERROR_RATE, P99_LATENCY_MS, AVG_DURATION_MS,
  THROUGHPUT, ERROR_COUNT).
- initialForm now returns a ready-to-save ROUTE_METRIC condition
  (metric=ERROR_RATE, comparator=GT, threshold=0.05, windowSeconds=300),
  so clicking through the wizard with all defaults produces a valid rule.
  Prevents a 400 'missing type id property kind' + 400 on condition enum
  validation if the user leaves the condition step untouched.

ui/src/pages/Alerts/RuleEditor/form-state.ts

@@ -51,7 +51,17 @@ export function initialForm(existing?: AlertRuleResponse): FormState {
       routeId: '',
       agentId: '',
       conditionKind: 'ROUTE_METRIC',
-      condition: { kind: 'ROUTE_METRIC' } as Partial<AlertCondition>,
+      // Pre-populate a valid ROUTE_METRIC default so a rule can be saved without
+      // the user needing to fill in every condition field. Values chosen to be
+      // sane for "error rate" alerts on almost any route.
+      condition: {
+        kind: 'ROUTE_METRIC',
+        scope: {},
+        metric: 'ERROR_RATE',
+        comparator: 'GT',
+        threshold: 0.05,
+        windowSeconds: 300,
+      } as unknown as Partial<AlertCondition>,
       evaluationIntervalSeconds: 60,
       forDurationSeconds: 0,
       reNotifyMinutes: 60,