Fix _normalize_ip_key to properly normalize IP addresses

Use ipaddress module instead of socket.inet_pton so that network host
bits are zeroed (e.g. 192.168.1.100/24 → 192.168.1.0/24) and IPv6
addresses are compressed (e.g. 2001:0db8:0000:… → 2001:db8::1).

https://claude.ai/code/session_01M3wRX9tnmc4qorVWRjmqTZ

Author: claude

src/ipdata/iptrie.py

@@ -16,7 +16,6 @@
 from __future__ import annotations
 
 import ipaddress
-import socket
 from collections.abc import Iterator
 from typing import TypeVar, Generic
 
@@ -53,18 +52,14 @@ def _normalize_ip_key(key: str) -> tuple[str, bool]:
     if not key:
         raise InvalidIPError("Key cannot be empty")
 
-    addr = key.rsplit("/", 1)[0] if "/" in key else key
-
-    try:
-        socket.inet_pton(socket.AF_INET, addr)
-        return key, False
-    except socket.error:
-        pass
-
     try:
-        socket.inet_pton(socket.AF_INET6, addr)
-        return key, True
-    except socket.error:
+        if "/" in key:
+            network = ipaddress.ip_network(key, strict=False)
+            return str(network), isinstance(network, ipaddress.IPv6Network)
+        else:
+            addr = ipaddress.ip_address(key)
+            return str(addr), isinstance(addr, ipaddress.IPv6Address)
+    except ValueError:
         raise InvalidIPError(f"Invalid IP address or network: {key!r}")