Find pull requests that have gone quiet

**Objective:** Find the active pull requests in `{repository-name}` (all repositories if empty) with no activity for `{stale-days}` days (default 7) and say what is holding each one up.

**Step 1: List active pull requests**

Call `azure-devops-get-pull-request` with status `active` and repository-name `{repository-name}` when given. Drop drafts from the main list and mention them separately. Keep those whose last activity is older than the stale threshold; use the creation-date when nothing newer is available.

**Step 2: Find the blockers**

For each stale pull request call `azure-devops-get-pull-request-reviewer` with its pull-request-id and repository-id. Note required reviewers with no vote, votes of waiting or rejected, and flagged reviewers. Then call `azure-devops-get-pull-request-thread` with the same ids and status `active` to count unresolved comment threads.

**Step 3: Report**

A table of pull request id, title, author, age in days, merge-status, reviewers still needed, unresolved threads. Below it, one line per pull request naming the single next action and who should take it. Order by age, oldest first.

**Rules & Guidelines:**

* This prompt is read-only. Call only the `azure-devops-get-*` read tools named above; never create, update, comment on, approve, queue, abort or delete anything in Azure DevOps.
* The tools only return data the connected account can see; never infer data from projects outside that access.
* Cap the deep dive at the 15 oldest stale pull requests and say how many were skipped.
* A merge-status other than succeeded is a blocker in its own right; call it out.

**Validation:**

* If no pull requests are stale, say so and show the oldest active one as a reference.
* If `{stale-days}` is empty, use 7.