Refactor GPU rental network handling and enhance IP management

- Renamed "FIP" to "IP" in the status output for clarity.
- Updated `create_gpu_server` to accept `port_id` as an optional parameter, allowing for more flexible network configurations.
- Introduced `delete_access_ip` function to manage direct public ports or floating IPs more effectively.
- Enhanced session management to prioritize direct public IPs over floating IPs, improving connection reliability.
- Added checks for direct network availability in the doctor command to ensure proper network functionality.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_session.py

@@ -144,8 +144,8 @@ def test_cmd_stop_deletes_compute_keeps_disks(monkeypatch):
         lambda conn, server, log: deleted.append(server.id),
     )
     monkeypatch.setattr(
-        "gpu_rent.session.delete_floating_ip",
-        lambda conn, fip_id, address, log: deleted.append("fip"),
+        "gpu_rent.session.delete_access_ip",
+        lambda conn, region, fip_id, address, log: deleted.append("fip"),
     )
     save_state(
         SessionState(