feat: enhance error handling in OAuth URL building and client creation; improve tool argument sanitization

src/model/session_lock.rs

@@ -32,6 +32,9 @@ impl SessionLock {
     }
 
     fn is_alive(&self, pid: u32) -> bool {
+        // SAFETY: `libc::kill(pid, 0)` does not send a signal; it only checks
+        // whether the process exists and the caller has permission to signal
+        // it. The integer argument is a PID already validated by `try_lock`.
         unsafe { libc::kill(pid as i32, 0) == 0 }
     }
 }