feat: add Activity type system, DB migration, and self-only showActivity in sanitizeUser

- Add Activity, ActivityType, ActivityTimestamps, ActivityAssets types to shared types
- Add activity_update client event and activities field on presence_update server event
- Add userActivities to ready payload and showActivity to User/UpdateUserRequest
- Create shared activities.ts with ACTIVITY_LIMITS, ACTIVITY_PRIORITY, getPrimaryActivity
- Add show_activity column to users table (schema + migration)
- Update sanitizeUser with isSelf parameter; only include showActivity for self
- Fix .map(sanitizeUser) calls to use arrow wrapper to prevent index-as-boolean bug
- Mark auth routes (register/login) as isSelf=true since they return own user data

packages/server/src/routes/auth.ts

@@ -122,7 +122,7 @@ export async function authRoutes(app: FastifyInstance): Promise<void> {
 
     const response: AuthResponse = {
       token,
-      user: sanitizeUser(user),
+      user: sanitizeUser(user, true),
     };
 
     return reply.code(201).send(response);
@@ -207,7 +207,7 @@ export async function authRoutes(app: FastifyInstance): Promise<void> {
 
     const response: AuthResponse = {
       token,
-      user: sanitizeUser({ ...user, status: 'online' }),
+      user: sanitizeUser({ ...user, status: 'online' }, true),
     };
 
     return reply.code(200).send(response);