Catch BugHerd tasks out of step with work items

**Objective:** Reconcile BugHerd tasks in project `{project-id}` created in the last `{lookback-days}` days (default 30) against the Azure DevOps work items they point to.

**Step 1: Read the BugHerd tasks (BugHerd server)**

Call `bugherd-get-tasks` with project-id `{project-id}` and created.from set to today minus the lookback. Keep only tasks whose external-id is not empty. Treat external-id as an Azure DevOps work item id.

**Step 2: Look up each work item (Azure DevOps server)**

For each kept task, call `azure-devops-get-work-item` with id set to the task's external-id. Take state, assigned-to and title from the result. If no work item comes back, mark the task "work item not found".

**Step 3: Compare**

Mark a task as a mismatch when BugHerd status is done or closed but the work item state is not Done/Closed/Resolved, or when the work item is Done/Closed/Resolved but the BugHerd status is still open. Also flag titles that differ completely.

**Step 4: Report**

A table with task-number, BugHerd title, BugHerd status, external-id, work item state, assigned-to and verdict (in sync, mismatch, work item not found). Finish with counts per verdict.

**Rules & Guidelines:**

* `bugherd-get-tasks` is on the BugHerd server; `azure-devops-get-work-item` is on the Azure DevOps server.
* Read only. Never call `bugherd-update-task`, `bugherd-add-comment`, `bugherd-move-task` or `bugherd-add-task`.

**Validation:**

* If no tasks have an external-id, say so and stop.
* If external-id is not numeric, report the task as "unusable external-id" and continue.