kvm2: config block, constructor registration, IDs, state mapping and classify

The kvm2 block reuses KVMConfig; validateKVM gains a block-name variant so
messages say kvm2. The package skeleton has a non-dialing New, strict
providerID parsing, the state table and a 34-row classify test.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

internal/provider/kvm2/state.go

@@ -0,0 +1,49 @@
+package kvm2
+
+import (
+	"net/netip"
+
+	"github.com/digitalocean/go-libvirt"
+
+	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
+)
+
+// mapState turns a libvirt domain state plus the discovered address into the
+// contract's state. nostate means libvirt could not tell, so the next poll
+// decides; an active domain is Running only once it has an address; every
+// inactive state, and anything unknown, is Stopped, which the reconciler
+// answers by replacing the instance.
+func mapState(s libvirt.DomainState, ip string) provider.InstanceState {
+	switch {
+	case s == libvirt.DomainNostate:
+		return provider.StateProvisioning
+	case isActive(s) && ip == "":
+		return provider.StateProvisioning
+	case isActive(s):
+		return provider.StateRunning
+	default:
+		return provider.StateStopped
+	}
+}
+
+func isActive(s libvirt.DomainState) bool {
+	return s == libvirt.DomainRunning || s == libvirt.DomainBlocked
+}
+
+// firstIPv4 picks the first usable IPv4 address from the guest's interfaces:
+// not loopback, not link-local, not unspecified. Empty means no address yet.
+func firstIPv4(ifaces []libvirt.DomainInterface) string {
+	for _, iface := range ifaces {
+		for _, a := range iface.Addrs {
+			if libvirt.IPAddrType(a.Type) != libvirt.IPAddrTypeIpv4 {
+				continue
+			}
+			addr, err := netip.ParseAddr(a.Addr)
+			if err != nil || !addr.Is4() || addr.IsLoopback() || addr.IsLinkLocalUnicast() || addr.IsUnspecified() {
+				continue
+			}
+			return addr.String()
+		}
+	}
+	return ""
+}