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>
