fix(support): agent-demo self-seeds (join default queue + go online); tickets always get a queue

Root cause of 'waiting for escalations': no queue/membership meant tickets were
never assigned. Now: createTicket find-or-creates a default queue; new joinDefault
endpoint + useGoOnline hook; agent-demo joins+goes-AVAILABLE on load (assignPending
picks up any waiting ticket). smoke-support self-seeds (no seed script needed).
Also: vitest singleFork to end cross-file DB races (45 tests deterministic).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/iios-service/src/support/support.controller.ts

@@ -63,6 +63,11 @@ export class SupportController {
     return this.assignment.addMember(id, this.principal(auth));
   }
 
+  @Post('agents/me/join')
+  async joinDefault(@Headers('authorization') auth?: string) {
+    return this.assignment.joinDefault(this.principal(auth));
+  }
+
   @Patch('members/me/availability')
   async availability(@Body() body: AvailabilityDto, @Headers('authorization') auth?: string) {
     return this.assignment.setAvailability(this.principal(auth), body.state);