uinput: configurable device identity with fallback to built-in defaults

Add vmctl_uinput_id and an optional vmctl_config.uinput_id pointer. NULL keeps the built-in identity verbatim; a non-NULL config supplies all numeric fields literally, with the device name suffixed -A/-B for the dual-device mode.

include/vmctl.h

@@ -19,11 +19,20 @@ typedef enum {
 #define VMCTL_PTR_REL   2   /* uinput: relative mouse             */
 #define VMCTL_PTR_BOTH  3   /* uinput: two devices A=abs B=rel    */
 
+typedef struct {
+    unsigned    bustype;     /* HID bus type, e.g. 0x0003 (USB)    */
+    unsigned    vendor;      /* vendor id                          */
+    unsigned    product;     /* product id                         */
+    unsigned    version;     /* device version                     */
+    const char* name;        /* device name; library copies it     */
+} vmctl_uinput_id;
+
 typedef struct {
     vmctl_driver driver;
     const char*  qmp_path;   /* QMP unix socket; required for QMP, optional (passthrough) for UINPUT */
     const char*  input_bus;  /* virtio-input-host-pci bus "pci.0" for passthrough; "" = none         */
     int          ptr_mode;   /* UINPUT VMCTL_PTR_*; 0 for QMP                                         */
+    const vmctl_uinput_id* uinput_id;  /* UINPUT only; NULL = built-in defaults                       */
 } vmctl_config;
 
 vmctl_t* vmctl_open (const vmctl_config* cfg);   /* NULL on error    */