fix(tests): correct ADDRESSES_RESPONSE fixture shape in TestGetInterfacesIp

Verified against a live OPNsense 24.7 instance: GET
/api/interfaces/overview/export returns a bare list of interface dicts
keyed by "device" with CIDR "addr4"/"addr6" strings, matching what
get_interfaces_ip() already parses. The fixture's "items"/"interface"/
"address"/"prefix" shape never matched, so all four TestGetInterfacesIp
tests failed regardless of driver correctness.

tests/unit/test_driver.py

@@ -61,13 +61,16 @@ INTERFACES_RESPONSE = {
     ]
 }
 
-ADDRESSES_RESPONSE = {
+# Real shape confirmed against a live OPNsense 24.7 instance's
-    "items": [
+# GET /api/interfaces/overview/export (see issue #14): a bare top-level list
-        {"interface": "em0", "address": "192.0.2.10", "prefix": 24},
+# of interface dicts, addressed via "device" and CIDR "addr4"/"addr6"
-        {"interface": "em0", "address": "2001:db8::1", "prefix": 64},
+# strings — not the "items"/"interface"/"address"/"prefix" shape this
-        {"interface": "em1", "address": "203.0.113.5", "prefix": 30},
+# fixture previously assumed, which never matched get_interfaces_ip()'s
+# actual parsing and made all four TestGetInterfacesIp tests fail.
+ADDRESSES_RESPONSE = [
+    {"device": "em0", "addr4": "192.0.2.10/24", "addr6": "2001:db8::1/64"},
+    {"device": "em1", "addr4": "203.0.113.5/30", "addr6": ""},
 ]
-}
 
 ARP_RESPONSE = {
     "arp": [