feat: auto-detect timezone/locale from proxy IP via geoip

Adds geoip=True parameter to launch(), launch_async(), and
launch_context(). Resolves proxy exit IP → MaxMind GeoLite2-City
lookup → timezone + locale. Downloads ~70MB DB on first use from
P3TERX mirror, caches in ~/.cloakbrowser/geoip/.

Optional deps: pip install cloakbrowser[geoip] / npm install mmdb-lib
Explicit timezone/locale always override auto-detected values.

pyproject.toml

@@ -46,6 +46,9 @@ dependencies = [
     "httpx>=0.24",
 ]
 
+[project.optional-dependencies]
+geoip = ["geoip2>=4.0"]
+
 [project.urls]
 Homepage = "https://github.com/CloakHQ/CloakBrowser"
 Documentation = "https://github.com/CloakHQ/CloakBrowser#readme"