Fix workspace dispatch: kanban workspace_kind is 'dir', block on dispatch 4xx

- Hermes rejects workspace_kind 'path' (valid: dir/scratch/worktree).
- Dispatch failure now blocks the work item with a dispatch.failed event
  instead of retrying the same 400 every tick.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

engine/dispatcher.py

@@ -113,8 +113,13 @@ class Dispatcher:
             )
             await self.hermes.dispatch_now()
         except HermesError as e:
+            # block instead of retrying every tick: dispatch 4xx is config, not transient
             log.warning("dispatch failed for %s: %s", item["id"], e)
             async with db.pool.connection() as conn:
+                async with conn.transaction():
+                    await conn.execute(
+                        "UPDATE work_item SET status='blocked', updated_at=now() WHERE id=%s",
+                        (item["id"],))
                     await db.append_event(conn, actor="system", event_type="dispatch.failed",
                                           company_id=item["company_id"], work_item_id=item["id"],
                                           payload={"error": str(e)[:300]})

engine/hermes_client.py

@@ -134,7 +134,7 @@ class HermesClient:
             "triage": False,
         }
         if workspace_path:
-            payload["workspace_kind"] = "path"
+            payload["workspace_kind"] = "dir"
             payload["workspace_path"] = workspace_path
         data = await self._json("POST", "/api/plugins/kanban/tasks", json=payload)
         return data.get("task", data)