feat: harden remote serve and reuse connections

- Gate TCP serve commands with safe-by-default policies, per-key allow tokens, per-key rate limiting, and audit labels.
- Reuse authenticated encrypted remote sessions and parallelize/caches multi-browser fanout to reduce repeated handshake roundtrips.
- Increase paged native-host batch size with extension-side byte budgeting to speed large tab listings safely.
- Point install output at public Chrome Web Store / Firefox AMO listings by default, with --dev preserving unpacked workflows.
- Share search-engine metadata between CLI and SDK and bump the package/extension version to 0.16.0.
- Cover the new security, pooling, paging, install, and fanout behavior with expanded Python and extension tests.

browser_cli/constants.py

@@ -20,11 +20,29 @@ FIREFOX_EXTENSION_ID = "browser-cli@yiprawr.dev"
 ALLOWED_EXTENSION_IDS = [EXTENSION_ID, WEBSTORE_EXTENSION_ID]
 SUPPORTED_BROWSERS = ["chrome", "chromium", "brave", "edge", "vivaldi", "firefox"]
 
+# Public store listings — the default install path now that the extension is
+# published. Chromium-family browsers (Brave/Edge/Vivaldi/Chromium) can all
+# install from the Chrome Web Store.
+CHROME_WEBSTORE_URL = f"https://chromewebstore.google.com/detail/browser-cli/{WEBSTORE_EXTENSION_ID}"
+FIREFOX_ADDON_URL = "https://addons.mozilla.org/firefox/addon/browser-cli/"
+
 PROTOCOL_MIN_CLIENT = "0.9.0"
 MAX_MSG_BYTES = 32 * 1024 * 1024
 DEFAULT_REMOTE_PORT = 443
-DEFAULT_PAGE_SIZE = 100
+# Count cap requested per page. The extension fills each page up to this many
+# items OR a byte budget (whichever comes first), so large items (e.g. data-URI
+# favicons) stay under the 1MB native-messaging limit while small items pack
+# into far fewer roundtrips.
+DEFAULT_PAGE_SIZE = 1000
+# Hard upper bound on total items collected across all pages, and the loop-guard
+# page count. Kept independent of page size so byte-budgeted small pages don't
+# falsely trip the guard.
+MAX_PAGED_ITEMS = 10_000
 DEFAULT_TRANSPORT_THRESHOLD = 512
+# How long a remote serve connection stays open waiting for the next command on
+# an established encrypted session before closing. Lets the client reuse one
+# authenticated connection for multiple commands instead of re-handshaking.
+REMOTE_SESSION_IDLE_TIMEOUT = 30
 
 NO_ROUTE_COMMANDS = {"browser-cli.targets", "browser-cli.auth.keys", "browser-cli.auth.trust"}
 GENTLE_MODES = ["auto", "normal", "gentle", "ultra"]