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/drizzle/meta/_journal.json

@@ -239,6 +239,13 @@
       "when": 1772409600000,
       "tag": "0033_drop_approval_columns",
       "breakpoints": true
+    },
+    {
+      "idx": 34,
+      "version": "6",
+      "when": 1772808163349,
+      "tag": "0034_salty_next_avengers",
+      "breakpoints": true
     }
   ]
 }