feat: Add errands schema, repository, and wire into tRPC context/container

Creates the errands table (with conflictFiles column), errand-repository
port interface, DrizzleErrandRepository adapter, and wires the repository
into TRPCContext, the DI container, _helpers.ts requireErrandRepository guard,
and the test harness. Also fixes pre-existing TS error in controller.test.ts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/server/agent/lifecycle/controller.test.ts

@@ -50,7 +50,6 @@ function makeController(overrides: {
     cleanupStrategy,
     overrides.accountRepository as AccountRepository | undefined,
     false,
-    overrides.eventBus,
   );
 }