feat: rewrite cloakserve as CDP multiplexer with per-connection fingerprint seeds

Spawns a separate Chrome process per unique fingerprint seed, all behind
a single port (9222). Clients specify seeds and fingerprint params via
query string on the CDP URL:

  connect_over_cdp("http://host:9222?fingerprint=12345&timezone=Asia/Tokyo")

Supports all --fingerprint-* flags as query params, geoip=true for
auto timezone/locale from proxy IP, and proxy= for per-process proxies.

- Rewrite bin/cloakserve from 57-line wrapper to aiohttp CDP multiplexer
- Add ChromePool with per-seed process management and port allocation
- Bidirectional WebSocket proxy for CDP traffic
- URL rewriting for /json/version, /json/list, and WS paths
- Rename _build_args -> build_args, _maybe_resolve_geoip -> maybe_resolve_geoip
- Add aiohttp + websockets to serve optional deps
- Dockerfile installs .[serve] extras
- Add 20 unit tests for cloakserve (param parsing, CLI args, URL rewriting)

cloakbrowser/__init__.py

@@ -11,7 +11,7 @@ Usage:
     browser.close()
 """
 
-from .browser import launch, launch_async, launch_context, launch_persistent_context, launch_persistent_context_async, ProxySettings
+from .browser import launch, launch_async, launch_context, launch_persistent_context, launch_persistent_context_async, ProxySettings, build_args, maybe_resolve_geoip
 from .config import CHROMIUM_VERSION, get_default_stealth_args
 from .download import binary_info, check_for_update, clear_cache, ensure_binary
 from ._version import __version__
@@ -40,6 +40,8 @@ __all__ = [
     "check_for_update",
     "CHROMIUM_VERSION",
     "get_default_stealth_args",
+    "build_args",
+    "maybe_resolve_geoip",
     "ProxySettings",
     "HumanConfig",
     "resolve_human_config",