fix: drop the needless try/catch around send_signal

Gio.Subprocess.send_signal returns void and is race-free, so it never throws.

strata@edu4rdshl.dev/extension.js

@@ -326,7 +326,7 @@ export default class StrataExtension extends Extension {
         if (!this._daemon) return;
         const daemon = this._daemon;
         this._daemon = null;
-        try { daemon.send_signal(15); } catch { /* already exited */ } // SIGTERM
+        daemon.send_signal(15); // SIGTERM
     }