host api alignment (#7)

* feat: add Firecracker API client methods for VM pause/resume and snapshots

Add PatchVm, GetVm, PutSnapshotCreate, and PutSnapshotLoad methods to the
API client, along with supporting types (VmState, SnapshotCreateParams,
SnapshotLoadParams, MemBackend).

* feat: add snapshot data layer - contract types, model, store, config

Add SnapshotID and snapshot contract types, SnapshotRecord model,
store interface CRUD methods with file store implementation,
snapshot paths helper, SnapshotsDir config, and directory creation.

* feat: add runtime methods for VM pause, resume, snapshot, and restore

Implement Pause, Resume, CreateSnapshot, and RestoreBoot on the
firecracker Runtime. RestoreBoot launches a jailer, stages snapshot
files into the chroot, loads the snapshot, and resumes the VM.

* feat: add daemon snapshot create, restore, and reconciliation logic

Implement CreateSnapshot (pause, snapshot, COW-copy disk, resume),
RestoreSnapshot (COW-copy disk, RestoreBoot, wait for guest),
GetSnapshot, ListSnapshots, DeleteSnapshotByID, and crash recovery
reconciliation for snapshot and restore operations.

* feat: add HTTP endpoints for snapshot create, get, list, delete, restore

Wire 5 snapshot routes: POST /machines/{id}/snapshots (create),
GET /machines/{id}/snapshots (list), GET /snapshots/{id} (get),
DELETE /snapshots/{id} (delete), POST /snapshots/{id}/restore (restore).

* fix: cross-device rename, restore network, and snapshot cleanup

- Replace os.Rename with copy+remove for moving snapshot files out of
  /proc/<pid>/root/ (cross-device link error on Linux)
- Reconfigure network interface after snapshot load so the restored VM
  uses its own tap device instead of the source VM's
- Clean partial snapshot dirs immediately on failure instead of only
  via reconcile
- Reject snapshot requests while a machine operation is already pending

* fix: test and modify snapshot runtime

* feat: snapshot lifecycle update, align runtime issues between host image
and daemon

internal/daemon/lifecycle.go

@@ -128,6 +128,14 @@ func (d *Daemon) Reconcile(ctx context.Context) error {
 			if err := d.reconcileDelete(ctx, operation.MachineID); err != nil {
 				return err
 			}
+		case model.MachineOperationSnapshot:
+			if err := d.reconcileSnapshot(ctx, operation); err != nil {
+				return err
+			}
+		case model.MachineOperationRestore:
+			if err := d.reconcileRestore(ctx, operation); err != nil {
+				return err
+			}
 		default:
 			return fmt.Errorf("unsupported operation type %q", operation.Type)
 		}
@@ -325,3 +333,36 @@ func (d *Daemon) detachVolumesForMachine(ctx context.Context, machineID contract
 	}
 	return nil
 }
+
+func (d *Daemon) reconcileSnapshot(ctx context.Context, operation model.OperationRecord) error {
+	if operation.SnapshotID == nil {
+		return d.store.DeleteOperation(ctx, operation.MachineID)
+	}
+	_, err := d.store.GetSnapshot(ctx, *operation.SnapshotID)
+	if err == nil {
+		// Snapshot completed successfully, just clear the journal
+		return d.store.DeleteOperation(ctx, operation.MachineID)
+	}
+	// Snapshot did not complete: clean up partial snapshot directory and resume the machine
+	snapshotDir := filepath.Join(d.config.SnapshotsDir, string(*operation.SnapshotID))
+	_ = os.RemoveAll(snapshotDir)
+
+	// Try to resume the source machine in case it was left paused
+	record, err := d.store.GetMachine(ctx, operation.MachineID)
+	if err == nil && record.Phase == contracthost.MachinePhaseRunning && record.PID > 0 {
+		_ = d.runtime.Resume(ctx, machineToRuntimeState(*record))
+	}
+	return d.store.DeleteOperation(ctx, operation.MachineID)
+}
+
+func (d *Daemon) reconcileRestore(ctx context.Context, operation model.OperationRecord) error {
+	_, err := d.store.GetMachine(ctx, operation.MachineID)
+	if err == nil {
+		// Restore completed, clear journal
+		return d.store.DeleteOperation(ctx, operation.MachineID)
+	}
+	// Restore did not complete: clean up partial machine directory and disk
+	_ = os.RemoveAll(filepath.Dir(d.systemVolumePath(operation.MachineID)))
+	_ = os.RemoveAll(d.machineRuntimeBaseDir(operation.MachineID))
+	return d.store.DeleteOperation(ctx, operation.MachineID)
+}