feat(alerting): AGENT_LIFECYCLE condition kind with per-subject fire mode

Allows alert rules to fire on agent-lifecycle events — REGISTERED,
RE_REGISTERED, DEREGISTERED, WENT_STALE, WENT_DEAD, RECOVERED — rather
than only on current state. Each matching `(agent, eventType, timestamp)`
becomes its own ackable AlertInstance, so outages on distinct agents are
independently routable.

Core:
- New `ConditionKind.AGENT_LIFECYCLE` + `AgentLifecycleCondition` record
  (scope, eventTypes, withinSeconds). Compact ctor rejects empty
  eventTypes and withinSeconds<1.
- Strict allowlist enum `AgentLifecycleEventType` (six entries matching
  the server-emitted types in `AgentRegistrationController` and
  `AgentLifecycleMonitor`). Custom agent-emitted event types tracked in
  backlog issue #145.
- `AgentEventRepository.findInWindow(env, appSlug, agentId, eventTypes,
  from, to, limit)` — new read path ordered `(timestamp ASC, insert_id
  ASC)` used by the evaluator. Implemented on
  `ClickHouseAgentEventRepository` with tenant + env filter mandatory.

App:
- `AgentLifecycleEvaluator` queries events in the last `withinSeconds`
  window and returns `EvalResult.Batch` with one `Firing` per row.
  Every Firing carries a canonical `_subjectFingerprint` of
  `"<agentId>:<eventType>:<tsMillis>"` in context plus `agent` / `event`
  subtrees for Mustache templating.
- `NotificationContextBuilder` gains an `AGENT_LIFECYCLE` branch that
  exposes `{{agent.id}}`, `{{agent.app}}`, `{{event.type}}`,
  `{{event.timestamp}}`, `{{event.detail}}`.
- Validation is delegated to the record compact ctor + enum at Jackson
  deserialization time — matches the existing policy of keeping
  controller validators focused on env-scoped / SQL-injection concerns.

Schema:
- V16 migration generalises the V15 per-exchange discriminator on
  `alert_instances_open_rule_uq` to prefer `_subjectFingerprint` with a
  fallback to the legacy `exchange.id` expression. Scalar kinds still
  resolve to `''` and keep one-open-per-rule. Duplicate-key path in
  `PostgresAlertInstanceRepository.save` is unchanged — the index is
  the deduper.

UI:
- New `AgentLifecycleForm.tsx` wizard form with multi-select chips for
  the six allowed event types + `withinSeconds` input. Wired into
  `ConditionStep`, `form-state` (validation + defaults: WENT_DEAD,
  300 s), and `enums.ts` options. Tests in `enums.test.ts` pin the
  new option array.
- `alert-variables.ts` registers `{{agent.app}}`, `{{event.type}}`,
  `{{event.timestamp}}`, `{{event.detail}}` leaves for the new kind,
  and extends `agent.id`'s availability list to include `AGENT_LIFECYCLE`.

Tests (all passing):
- 5 new JSON-roundtrip cases on `AlertConditionJsonTest` (positive +
  empty/zero/unknown-type rejection).
- 5 new evaluator unit tests on `AgentLifecycleEvaluatorTest` (empty
  window, multi-agent fingerprint shape, scope forwarding, missing env).
- `NotificationContextBuilderTest` switch now covers the new kind.
- 119 alerting unit tests + 71 UI tests green.

Docs: `.claude/rules/{core,app,ui}` and CLAUDE.md migration list updated.

.claude/rules/app-classes.md

@@ -65,8 +65,8 @@ Env-scoped read-path controllers (`AlertController`, `AlertRuleController`, `Ale
 - `AgentEventsController` — GET `/api/v1/environments/{envSlug}/agents/events` (lifecycle events; cursor-paginated, returns `{ data, nextCursor, hasMore }`; order `(timestamp DESC, insert_id DESC)`; cursor is base64url of `"{timestampIso}|{insert_id_uuid}"` — `insert_id` is a stable UUID column used as a same-millisecond tiebreak).
 - `AgentMetricsController` — GET `/api/v1/environments/{envSlug}/agents/{agentId}/metrics` (JVM/Camel metrics). Rejects cross-env agents (404) as defence-in-depth.
 - `DiagramRenderController` — GET `/api/v1/environments/{envSlug}/apps/{appSlug}/routes/{routeId}/diagram` (env-scoped lookup). Also GET `/api/v1/diagrams/{contentHash}/render` (flat — content hashes are globally unique).
-- `AlertRuleController` — `/api/v1/environments/{envSlug}/alerts/rules`. GET list / POST create / GET `{id}` / PUT `{id}` / DELETE `{id}` / POST `{id}/enable` / POST `{id}/disable` / POST `{id}/render-preview` / POST `{id}/test-evaluate`. OPERATOR+ for mutations, VIEWER+ for reads. CRITICAL: attribute keys in `ExchangeMatchCondition.filter.attributes` are validated at rule-save time against `^[a-zA-Z0-9._-]+$` — they are later inlined into ClickHouse SQL. Webhook validation: verifies `outboundConnectionId` exists and `isAllowedInEnvironment`. Null notification templates default to `""` (NOT NULL constraint). Audit: `ALERT_RULE_CHANGE`.
-- `AlertController` — `/api/v1/environments/{envSlug}/alerts`. GET list (inbox filtered by userId/groupIds/roleNames via `InAppInboxQuery`) / GET `/unread-count` / GET `{id}` / POST `{id}/ack` / POST `{id}/read` / POST `/bulk-read`. VIEWER+ for all. Inbox SQL: `? = ANY(target_user_ids) OR target_group_ids && ? OR target_role_names && ?` — requires at least one matching target (no broadcast concept).
+- `AlertRuleController` — `/api/v1/environments/{envSlug}/alerts/rules`. GET list / POST create / GET `{id}` / PUT `{id}` / DELETE `{id}` / POST `{id}/enable` / POST `{id}/disable` / POST `{id}/render-preview` / POST `{id}/test-evaluate`. OPERATOR+ for mutations, VIEWER+ for reads. CRITICAL: attribute keys in `ExchangeMatchCondition.filter.attributes` are validated at rule-save time against `^[a-zA-Z0-9._-]+$` — they are later inlined into ClickHouse SQL. `AgentLifecycleCondition` is allowlist-only — the `AgentLifecycleEventType` enum (REGISTERED / RE_REGISTERED / DEREGISTERED / WENT_STALE / WENT_DEAD / RECOVERED) plus the record compact ctor (non-empty `eventTypes`, `withinSeconds ≥ 1`) do the validation; custom agent-emitted event types are tracked in backlog issue #145. Webhook validation: verifies `outboundConnectionId` exists and `isAllowedInEnvironment`. Null notification templates default to `""` (NOT NULL constraint). Audit: `ALERT_RULE_CHANGE`.
+- `AlertController` — `/api/v1/environments/{envSlug}/alerts`. GET list (inbox filtered by userId/groupIds/roleNames via `InAppInboxQuery`; optional multi-value `state` + `severity` query params push filtering into PostgreSQL via `listForInbox` with `state::text = ANY(?)` / `severity::text = ANY(?)`) / GET `/unread-count` / GET `{id}` / POST `{id}/ack` / POST `{id}/read` / POST `/bulk-read`. VIEWER+ for all. Inbox SQL: `? = ANY(target_user_ids) OR target_group_ids && ? OR target_role_names && ?` — requires at least one matching target (no broadcast concept).
 - `AlertSilenceController` — `/api/v1/environments/{envSlug}/alerts/silences`. GET list / POST create / DELETE `{id}`. 422 if `endsAt <= startsAt`. OPERATOR+ for mutations, VIEWER+ for list. Audit: `ALERT_SILENCE_CHANGE`.
 - `AlertNotificationController` — Dual-path (no class-level prefix). GET `/api/v1/environments/{envSlug}/alerts/{alertId}/notifications` (VIEWER+); POST `/api/v1/alerts/notifications/{id}/retry` (OPERATOR+, flat — notification IDs globally unique). Retry resets attempts to 0 and sets `nextAttemptAt = now`.