fix(dns): handle empty and invalid IP addresses gracefully

Add guard checks to prevent panics when processing client info with
empty IP addresses. Replace netip.MustParseAddr with ParseAddr to
handle invalid IP addresses gracefully instead of panicking.

Add test to verify queryFromSelf handles IP addresses safely.

cmd/cli/dns_proxy_test.go

@@ -794,6 +794,16 @@ func Test_handleRecovery_Integration(t *testing.T) {
 	}
 }
 
+func Test_prog_queryFromSelf(t *testing.T) {
+	p := newTestProg(t)
+	require.NotPanics(t, func() {
+		p.queryFromSelf("")
+	})
+	require.NotPanics(t, func() {
+		p.queryFromSelf("foo")
+	})
+}
+
 // newTestProg creates a properly initialized *prog for testing.
 func newTestProg(t *testing.T) *prog {
 	p := &prog{cfg: testhelper.SampleConfig(t)}