fix(presence): reset stale users.status on boot; drop REST-login online write

users.status was only flipped back to offline by the WebSocket disconnect
path (5s grace timer in ConnectionManager). Process exits (deploy/crash/OOM)
lose those in-memory timers, freezing any non-offline row at its last value
and making the user appear permanently online to friends and space co-members.
Confirmed in production on the Pi instance: a user appeared online for ~3
days with no live socket.

Add resetStalePresenceOnBoot() in utils/presenceBoot.ts and call it from
index.ts after getDb()/seedDatabase() and before WebSocket route registration.
The reset is federation-safe: it only updates rows where home_instance IS
NULL (replicated stubs are projections of remote presence and must not be
stomped) and is_deleted = 0 (tombstoned users are excluded from broadcasts).

Also remove the redundant status='online' write from POST /api/auth/login.
A successful REST login does not imply a live socket; the WS auth handshake
is the single source of truth. Login alone could otherwise produce the same
stuck-online row when a client logs in and never establishes a WS.

Tests cover: locally-homed online/idle/dnd reset, replicated rows untouched,
tombstoned rows untouched, idempotence, mixed populations.

Updates docs/systems/activity-presence.md (Connect/Disconnect Flow, new Boot
Reset section) and docs/systems/auth.md (login no longer mutates status).

packages/server/src/index.ts

@@ -28,6 +28,7 @@ import { federationRoutes } from './routes/federation.js';
 import { startFederationWorkers, stopFederationWorkers } from './utils/federationWorker.js';
 import './utils/federationRollback.js'; // Side-effect: registers rollback callbacks for outbox terminal failures.
 import { registerCallRelayHooks } from './ws/events.js';
+import { resetStalePresenceOnBoot } from './utils/presenceBoot.js';
 
 import { registerWebSocket } from './ws/handler.js';
 import path from 'path';
@@ -82,6 +83,14 @@ async function main(): Promise<void> {
   getDb();
   await seedDatabase();
 
+  // Reset orphaned `users.status` rows for locally-homed users. The previous
+  // process's in-memory disconnect timers are gone, so any non-offline row
+  // is stale by construction. Replicated (federated) rows are skipped — their
+  // status is a projection of remote presence, not local WS state. Must run
+  // before WS auth is accepted so the first connection broadcasts the correct
+  // online transition. See utils/presenceBoot.ts.
+  resetStalePresenceOnBoot();
+
   await app.register(authRoutes);
   await app.register(userRoutes);
   await app.register(spaceRoutes);