controller v0.49.0: slice 10 P2 activation — pending-drive detection + restart button

pendingActivationDrives() flags registered drives the agent shows attached but not
live-mounted in the container; settings banner + "Újraindítás most" button →
/api/storage/activate → agentapi.GuestReboot. Batches all pending into one restart.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

controller/internal/agentapi/client.go

@@ -331,6 +331,15 @@ func (c *Client) GuestAttach(ctx context.Context, where string) error {
 	return err
 }
 
+// GuestReboot reboots THIS guest to activate persisted-but-inactive drive binds (slice 10 P2
+// activation — the host-side live inject is blocked on an unprivileged guest, so a drive enrolled into
+// a running guest activates only at the next boot). The agent runs the reboot detached + returns 202;
+// this guest (and the controller) restarts shortly after. User-triggered ("Újraindítás most").
+func (c *Client) GuestReboot(ctx context.Context) error {
+	_, err := c.post(ctx, "/guest/reboot", struct{}{})
+	return err
+}
+
 // EjectResult mirrors POST /disks/eject (the dependent-guest warning).
 type EjectResult struct {
 	VMID            int    `json:"vmid"`