This change improves the robustness of the llama.cpp extension's server port selection.
Previously, the `getRandomPort()` method only checked for ports already in use by active sessions, which could lead to model load failures if the chosen port was occupied by another external process.
This change introduces a new Tauri command, `is_port_available`, which performs a system-level check to ensure the randomly selected port is truly free before attempting to start the llama-server. It also adds a retry mechanism with a maximum number of attempts (20,000) to find an available port, throwing an error if no suitable port is found within the specified range after all attempts.
This enhancement prevents port conflicts and improves the reliability and user experience of the llama.cpp extension within Jan.
Closes#5965
f61ce886a0