Harden Windows Server compatibility and system-wide proxy.

Fix exit-IP checks for HTTP-only proxies, apply proxy via WinINet Connections blob and WinHTTP, improve VPN detection on legacy Server, add SOCKS5 host:port:user:pass exit parsing, and add win_compat probe for PowerShell 2.0 hosts.

Co-authored-by: Cursor <cursoragent@cursor.com>

proxy_chain_manager/fingerprint.py

@@ -11,6 +11,7 @@ from dataclasses import dataclass, field
 
 from .firewall import is_admin
 from .mac_spoof import list_nics
+from .win_compat import probe as _win_probe
 
 log = logging.getLogger(__name__)
 
@@ -106,6 +107,11 @@ def disable_ipv6_on_adapters() -> tuple[list[str], list[str]]:
     """Disable IPv6 binding on up physical adapters. Returns (adapter names, log lines)."""
     if not is_admin():
         return [], ["IPv6 disable skipped (not Admin)."]
+    if not _win_probe().has_net_cmdlets:
+        return [], [
+            "IPv6 disable skipped — requires PowerShell 3.0+ "
+            "(Windows 8 / Server 2012+). Detected legacy PowerShell."
+        ]
     script = (
         "Get-NetAdapter | Where-Object { $_.Status -eq 'Up' } | "
         "ForEach-Object { $_.Name }"
@@ -135,6 +141,8 @@ def disable_ipv6_on_adapters() -> tuple[list[str], list[str]]:
 def enable_ipv6_on_adapters(adapters: list[str]) -> list[str]:
     if not is_admin() or not adapters:
         return []
+    if not _win_probe().has_net_cmdlets:
+        return []
     logs: list[str] = []
     for name in adapters:
         cmd = (