fix(security): handle IPv6 scope IDs in URL safety checks to prevent bypass

ipaddress.ip_address() raises ValueError on IPv6 addresses with scope
IDs (e.g. 'fe80::1%eth0'). Both is_always_blocked_url() and is_safe_url()
silently skipped these via `except ValueError: continue`.

If ALL resolved addresses for a hostname carry scope IDs, every address
is skipped and the URL passes all safety checks — a potential SSRF
bypass vector against link-local or metadata endpoints.

Fix:
- Strip the scope ID (%eth0) before parsing in both functions
- is_safe_url(): fail closed (return False) with a warning log if still
  unparseable after stripping
- is_always_blocked_url(): use continue (not return False) to preserve
  multi-address scanning, with a warning log

Affected: tools/url_safety.py — is_always_blocked_url(), is_safe_url()

tools/url_safety.py

@@ -282,9 +282,12 @@ def is_always_blocked_url(url: str) -> bool:
 
         for _family, _, _, _, sockaddr in addr_info:
             ip_str = sockaddr[0]
+            if '%' in ip_str:
+                ip_str = ip_str.split('%')[0]
             try:
                 resolved = ipaddress.ip_address(ip_str)
             except ValueError:
+                logger.warning("Unparseable IP address %r for hostname %s — skipping address", sockaddr[0], hostname)
                 continue
             if resolved in _ALWAYS_BLOCKED_IPS or any(
                 resolved in net for net in _ALWAYS_BLOCKED_NETWORKS
@@ -353,10 +356,14 @@ def is_safe_url(url: str) -> bool:
 
         for family, _, _, _, sockaddr in addr_info:
             ip_str = sockaddr[0]
+            if '%' in ip_str:
+                ip_str = ip_str.split('%')[0]
             try:
                 ip = ipaddress.ip_address(ip_str)
             except ValueError:
-                continue
+                # Still unparseable after scope ID strip — fail closed
+                logger.warning("Blocked request — unparseable IP address %r for hostname %s", sockaddr[0], hostname)
+                return False
 
             # Always block cloud metadata IPs and link-local, even with toggle on
             if ip in _ALWAYS_BLOCKED_IPS or any(ip in net for net in _ALWAYS_BLOCKED_NETWORKS):