proxmox: config block, IDs, marks, state mapping, classify, registration

Phase 2 of the proxmox provider plan. Adds the proxmox: config block with
its validation, registers the type in the config allow-list and the
constructor map, and starts internal/provider/proxmox: the api seam and
its data types, providerIDs (vms/<vmid>/<name>) with the UID-derived VMID,
the description mark, state mapping, and error classification.

Tests read the responses captured from pv1-1 in Phase 0 rather than
repeating Proxmox's wording, and every matcher is run against every
captured error so none fires on the wrong message. The contract methods
are Transient stubs until Phases 5 to 7.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

internal/provider/proxmox/state.go

@@ -0,0 +1,52 @@
+package proxmox
+
+import (
+	"net/netip"
+
+	"gitea.home.hrajfrisbee.cz/kacerr/egress-proxies-operator/internal/provider"
+)
+
+// mapState turns status/current's status and qmpstatus plus the discovered
+// address into the contract's state (spec entry 9). A VM is Running only
+// with an address; prelaunch is still starting; any other qmpstatus of a
+// running VM (paused, suspended, io-error, …) and any status not recognised
+// is Stopped, which the reconciler answers by replacing the VM. An empty
+// qmpstatus is taken as running: the field is missing, not a state.
+func mapState(status, qmpStatus, ip string) provider.InstanceState {
+	if status != "running" {
+		return provider.StateStopped
+	}
+	switch qmpStatus {
+	case "running", "":
+		if ip == "" {
+			return provider.StateProvisioning
+		}
+		return provider.StateRunning
+	case "prelaunch":
+		return provider.StateProvisioning
+	default:
+		return provider.StateStopped
+	}
+}
+
+// firstIPv4 picks the first usable IPv4 from the guest agent's interfaces,
+// in the agent's order: not on the loopback interface, not loopback,
+// link-local or unspecified. Empty means no address yet.
+func firstIPv4(ifaces []agentInterface) string {
+	for _, iface := range ifaces {
+		if iface.Name == "lo" {
+			continue
+		}
+		for _, a := range iface.IPAddresses {
+			if a.Type != "ipv4" {
+				continue
+			}
+			addr, err := netip.ParseAddr(a.Address)
+			if err != nil || !addr.Is4() || addr.IsLoopback() || addr.IsLinkLocalUnicast() || addr.IsUnspecified() {
+				continue
+			}
+			return addr.String()
+		}
+	}
+	return ""
+}