fix: register errand router in appRouter and fix build errors

errandProcedures was defined but never imported/spread into the app
router, causing "No procedure found on path errand.create". Also fixed
nullable projectId TS errors in delete/abandon and added missing
sendUserMessage to test mocks.

apps/server/test/unit/headquarters.test.ts

@@ -63,6 +63,7 @@ class MockAgentManager implements AgentManager {
   async delete(): Promise<void> { throw new Error('Not implemented'); }
   async dismiss(): Promise<void> { throw new Error('Not implemented'); }
   async resumeForConversation(): Promise<boolean> { return false; }
+  async sendUserMessage(): Promise<void> { throw new Error('Not implemented'); }
 }
 
 // =============================================================================

apps/server/test/unit/radar-procedures.test.ts

@@ -69,6 +69,7 @@ class MockAgentManager implements AgentManager {
   async delete(): Promise<void> { throw new Error('Not implemented'); }
   async dismiss(): Promise<void> { throw new Error('Not implemented'); }
   async resumeForConversation(): Promise<boolean> { return false; }
+  async sendUserMessage(): Promise<void> { throw new Error('Not implemented'); }
 }
 
 // =============================================================================