Phase 7: Bot/extension system

Bot accounts (User rows with is_bot=True), scoped API tokens (read:messages,
write:messages, manage:rooms) authenticated via Authorization: Bearer on both
REST and the WS handshake, live bot WebSocket access on the same /ws/chat
endpoint humans use, message editing (WS "edit" envelope -> message_update
broadcast, fans out cross-instance for free via the existing broadcaster),
incoming webhooks (room-scoped, no auth beyond the URL token), and outgoing
webhooks/event subscriptions (HMAC-SHA256 signed, backgrounded delivery,
creation-time SSRF validation against private/loopback/link-local targets).

Token auth is additive, not a parallel system: a bearer-token-authenticated
bot goes through the exact same room-membership/role checks a session-
authenticated human does everywhere; only read:messages/write:messages are
separately scope-gated (the two message endpoints). manage:rooms scope
enforcement, full per-delivery SSRF re-validation, and bot API rate limiting
were explicitly scoped out (confirmed with the repo owner) as disproportionate
to this phase -- documented as known gaps in backend/README.md rather than
silently skipped.

Admin portal gains a Bots tab (create bots, issue/revoke scoped tokens,
cross-room webhook visibility); RoomInfoPanel gains room-scoped webhook/
subscription management, mirroring how invites already work there. The chat
UI also gets a minimal "edit your own message" affordance -- not asked for
by the issue, but the only practical way to exercise the edit pipeline by
hand instead of only via a scripted bot client.

Along the way: fixed a real bug caught while writing the incoming-webhook
test -- offline-push notification relied on the sender being "connected" to
exclude themselves, true for WS-originated messages but not for the new
webhook path, which has no WS connection for the attributed sender at all.
Now explicitly excluded. Also discovered the REST-only test fixture never
triggered ASGI lifespan, so app.state.broadcaster/presence didn't exist for
it; moved their construction out of the lifespan into create_app() itself
(Redis client construction is synchronous/lazy) so both the WS and
REST-only paths always have them.

New tests/test_bots.py, test_message_edit.py, test_webhooks.py (full suite
now 78/78, stable across repeated runs) plus a scripted end-to-end smoke
test (bot WS join/post/edit, incoming webhook, SSRF rejection, outgoing
delivery) and a full browser walkthrough of the new admin/room UI.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/api/admin.ts

@@ -1,5 +1,11 @@
 import { apiFetch } from './client'
-import type { AdminRoom, AdminUser, AuditLogEntry } from '../types'
+import type {
+  AdminRoom,
+  AdminUser,
+  AuditLogEntry,
+  EventSubscriptionAdmin,
+  WebhookIncomingAdmin,
+} from '../types'
 
 export function listAdminUsers(): Promise<AdminUser[]> {
   return apiFetch<AdminUser[]>('/api/admin/users')
@@ -50,3 +56,11 @@ export function transferOwnershipAdmin(roomId: string, newOwnerId: string): Prom
 export function listAuditLog(limit = 50, offset = 0): Promise<AuditLogEntry[]> {
   return apiFetch<AuditLogEntry[]>(`/api/admin/audit-log?limit=${limit}&offset=${offset}`)
 }
+
+export function listAllIncomingWebhooks(): Promise<WebhookIncomingAdmin[]> {
+  return apiFetch<WebhookIncomingAdmin[]>('/api/admin/webhooks/incoming')
+}
+
+export function listAllEventSubscriptions(): Promise<EventSubscriptionAdmin[]> {
+  return apiFetch<EventSubscriptionAdmin[]>('/api/admin/event-subscriptions')
+}