feat: include watchers in issue details and update API call parameters

app/client.py

@@ -31,7 +31,7 @@ def _post(path: str, body: dict) -> dict:
     with httpx.Client(timeout=15) as client:
         resp = client.post(url, headers=_headers(), content=json.dumps(body))
         resp.raise_for_status()
-        return resp.json()
+        return resp.json() if resp.content else {}
 
 
 def _delete(path: str) -> None:

app/entities/issues.py

@@ -71,9 +71,9 @@ def get_issue(issue_id: int) -> str:
     """
     Get a Redmine issue by ID.
     Returns full issue details: title, description, status, priority,
-    assignee, progress, dates, custom fields.
+    assignee, progress, dates, custom fields, watchers.
     """
-    data = _get(f"/issues/{issue_id}.json")
+    data = _get(f"/issues/{issue_id}.json", params={"include": "watchers"})
     return json.dumps(data["issue"], ensure_ascii=False, indent=2)