[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/src/app_internal.h

@@ -25,5 +25,10 @@
 
 void app_handleKeyPressInternal(int scancode);
 void app_handleKeyReleaseInternal(int scancode);
+void app_handleButtonPressInternal(int button);
+void app_handleButtonReleaseInternal(int button);
+void app_handleKeyboardModifiersInternal(
+    bool ctrl, bool shift, bool alt, bool super);
+void app_handleInputResetInternal(bool keyboard, bool pointer);
 
 #endif