fix(connect): never fall back to the consent-dialog raw port when the extension is installed

Root cause of the recurring "Allow remote debugging?" dialog: when the ab-connect
relay was momentarily down (MV3 service worker drops the relay-url file across a
Chrome restart / idle wake), auto_connect_cdp silently fell through to the raw
:9222 DevToolsActivePort path — which pops Chrome 136+'s consent modal, the exact
thing the extension exists to avoid. Even a relay-aware build hit this if it
connected during the blip.

Fix: if the native-messaging host is installed (connect::host_installed() — the
durable signal that the user chose the extension path), auto_connect retries the
relay for ~5s while the SW reconnects, and then ERRORS with an actionable message
instead of attaching to a raw debug port. The raw :9222 path now runs only when
no extension is set up (where the dialog is expected). `--cdp <port>` still forces
the raw path explicitly.

cli/src/connect.rs

@@ -344,6 +344,19 @@ fn host_manifest_path_for_chrome() -> Option<PathBuf> {
         })
 }
 
+/// True if the ab-connect native-messaging host manifest is present — i.e. the
+/// user has set up the extension path. When installed, auto-connect treats the
+/// dialog-free extension relay as the *intended* transport and refuses to fall
+/// back to a raw debug port (which would pop Chrome 136+'s "Allow remote
+/// debugging?" consent modal). The relay-url file comes and goes with the
+/// service worker; this manifest is the durable signal that the extension is
+/// the chosen path.
+pub fn host_installed() -> bool {
+    native_messaging_dirs()
+        .into_iter()
+        .any(|d| d.join(format!("{HOST_NAME}.json")).exists())
+}
+
 fn report(json: bool, ok: bool, msg: &str) {
     if json {
         println!(