vmsig: management daemon, runtime endpoint lifecycle, roster, discovery, in-tree drivers, packaging

- core: runtime attach/detach of a per-endpoint adapter trio (runtime-safe add_adapter + vmsig_core_detach_endpoint, deferred reap)
- roster: VMSIG_EV_ROSTER + CAP_ROSTER, retained per-endpoint and replayed to late subscribers
- discovery: inotify trigger dir, vmid/endpoint slot allocator, host probe; vmsigd daemon with config + per-uid admission
- input driver and vgpu perception built in-tree; vgpu perception as a separate library
- memctx: own the supplied ro_fd (closed at detach)
- deb packaging: install rules, systemd unit, tmpfiles, default config

src/si/input/include/driver.h

@@ -0,0 +1,39 @@
+#ifndef VMCTL_DRIVER_H
+#define VMCTL_DRIVER_H
+#include "vmctl.h"
+#include "qmp.h"
+
+/* driver.h — input-driver vtable, the concrete vmctl handle, and the shared
+ * event-kind enum. The event kind is the SINGLE source of truth that every
+ * driver switches on (never on magic numbers). */
+
+typedef enum {
+    VMCTL_EV_ABS, VMCTL_EV_REL, VMCTL_EV_BTN, VMCTL_EV_KEY, VMCTL_EV_SCROLL
+} vmctl_ev_kind;
+
+typedef struct {
+    int  (*send)(vmctl_t* v, const vmctl_batch* b);   /* deliver an input batch        */
+    void (*close)(vmctl_t* v);                        /* release driver resources      */
+} vmctl_driver_ops;
+
+struct vmctl {
+    vmctl_driver_ops ops;
+    vmctl_driver     driver;
+    qmp_conn*        qmp;       /* control channel; NULL if none            */
+    int              ui_fd_a;   /* uinput driver: device A; -1 for QMP      */
+    int              ui_fd_b;   /* uinput driver: device B (BOTH); -1       */
+    int              ptr_mode;  /* uinput driver: VMCTL_PTR_*; 0 for QMP    */
+
+    /* Held-state receipt: key/btn down-bits as THIS handle last actuated them
+     * (not guest truth). Written only after a successful send in
+     * vmctl_batch_send; the send path never reads them. Zero-initialised by
+     * calloc at open = all up. Single-threaded (one handle owner): no locks. */
+    unsigned char    keys_held[VMCTL_KEYS_SNAPSHOT_BYTES]; /* evdev-indexed key down-bits  */
+    unsigned         btns_held;                            /* VMCTL_BTN_* 0..7 down-bits   */
+};
+
+/* driver factories (called from open.c per cfg->driver) */
+vmctl_t* vmctl_open_qmp_driver   (const vmctl_config* cfg);
+vmctl_t* vmctl_open_uinput_driver(const vmctl_config* cfg);
+
+#endif /* VMCTL_DRIVER_H */