fix: AOS-Switch REST API session cookie auth and VLAN PUT body

connect() never sent back the sessionId returned in the login response
body, so all writes (POST/PUT/DELETE) were silently rejected with
"Access is unauthorized" while reads worked fine. Also fix
_api_set_vlan to PUT the full VLAN object (AOS-Switch v3 rejects
partial PUT bodies with HTTP 400).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

napalm_procurve/procurve.py

@@ -765,8 +765,11 @@ class ProcurveDriver(SwitchDriver):
         resp = self._api.post("vlans", json=payload)
         if not resp.ok:
             if resp.status_code in (400, 409):
-                # VLAN already exists — update name via PUT
-                resp2 = self._api.put(f"vlans/{vlan_id}", json={"name": name})
+                # VLAN already exists — PUT requires the full VLAN object
+                existing = self._api.get(f"vlans/{vlan_id}")
+                existing.pop("uri", None)
+                existing["name"] = name
+                resp2 = self._api.put(f"vlans/{vlan_id}", json=existing)
                 if not resp2.ok:
                     raise ConnectionException(
                         f"set_vlan({vlan_id}): API PUT returned HTTP {resp2.status_code}"