fix(connect): keep native-messaging host as com.agent_browser.connect (no relay break)

Reverting the host-name rename from the chrome-use rebrand. The host name is
invisible internal plumbing (lives only in NativeMessagingHosts/*.json and the
extension), so renaming it to com.leeguoo.chrome_use bought nothing user-facing
but broke the relay for every existing user: the new chrome-use binary couldn't
find a matching host/extension, silently fell back to raw --remote-debugging-port,
and re-popped the 'Allow remote debugging?' consent dialog.

Keeping com.agent_browser.connect means the renamed chrome-use binary keeps
working with the already-installed host json and the live ab-connect 0.4.2
extension — zero relay break, no dialog, and the store republish becomes an
OPTIONAL cosmetic display-name update (manifest bumped 0.5.0 → 0.4.3, name stays
chrome-use). Only the binary/command name changed for users.

extensions/ab-connect/background.js

@@ -16,7 +16,7 @@
 // attach + Target handling; the transport is rewritten from WebSocket+token to
 // native messaging.
 
-const HOST_NAME = 'com.leeguoo.chrome_use'
+const HOST_NAME = 'com.agent_browser.connect'
 const SKIP_URL = /^(chrome|chrome-extension|devtools|chrome-untrusted|edge|about):/i
 
 /** @type {chrome.runtime.Port|null} */