[client] evdev: fix input capture and device handling

Classify configured devices by keyboard and pointer capability so
automatic keyboard capture leaves relative pointer devices with the
display server.

Run descriptor, grab, physical-state, and LED operations on one worker.
Marshal normalized events through each display server's event loop and
serialize ownership changes with per-lane barriers.

Fall back whole lanes to native input when an evdev cohort cannot be
owned, and retry missing or removed devices without disabling the rest.

Handle report framing, SYN_DROPPED, high-resolution wheels, queue
overflow, held-state cleanup, and guest-driven keyboard LEDs. Restore
host LEDs and kernel grabs during teardown.

Re-evaluate capture when the active input transport changes.

client/include/input.h

@@ -25,6 +25,7 @@
 
 typedef void (*LGInputKeyboardLEDsFn)(void * opaque,
     bool valid, uint8_t leds);
+typedef void (*LGInputAvailabilityFn)(void * opaque, bool available);
 
 void lgInput_init(void);
 void lgInput_free(void);
@@ -43,11 +44,20 @@ bool lgInput_supports(LG_InputSupport support);
  * call back into the input layer. */
 void lgInput_setKeyboardLEDsListener(
     LGInputKeyboardLEDsFn callback, void * opaque);
+/* The listener is called synchronously with the current input availability
+ * and later from transport threads whenever it changes. The callback must
+ * not call back into the input layer. */
+void lgInput_setAvailabilityListener(
+    LGInputAvailabilityFn callback, void * opaque);
 
 bool lgInput_keyDown(int key);
 bool lgInput_keyUp(int key);
 bool lgInput_keyboardLEDs(bool numLock, bool capsLock, bool scrollLock);
 void lgInput_releaseKeys(void);
+void lgInput_releaseButtons(void);
+/* Release all tracked keyboard and mouse button state under one active-input
+ * transaction. */
+void lgInput_releaseAll(void);
 
 bool lgInput_mouseMotion(int32_t x, int32_t y);
 bool lgInput_mousePosition(uint32_t x, uint32_t y, uint32_t width,