feat: native SOCKS5 proxy support in proxy= parameter

Route SOCKS5/SOCKS5h proxies via --proxy-server Chrome arg instead of
Playwright's proxy dict (which rejects SOCKS5 with credentials).
Handles string URLs, Playwright dicts, IPv6, bypass lists.

SOCKS5 geoip exit IP resolution uses socks-proxy-agent (optional peer
dep). Falls back to DNS if not installed.

pyproject.toml

@@ -54,7 +54,7 @@ dependencies = [
 ]
 
 [project.optional-dependencies]
-geoip = ["geoip2>=4.0"]
+geoip = ["geoip2>=4.0", "socksio>=1.0"]  # socksio: SOCKS5 transport for httpx
 patchright = ["patchright>=1.40"]
 serve = ["aiohttp>=3.9", "websockets>=12.0"]
 dev = ["pytest>=7.0", "pytest-asyncio>=0.23"]