Key bindings layer: skills on 1-7, weapon sets on F1-F7

Raw WM_KEYDOWN/WM_KEYUP are handled in both window procedures (the game
swaps 0x8110d0 and 0x8122a0 with SetWindowLong; 0x8110d0 is the in-game
one). Bound keys are swallowed and post the original hotkey's key event
to the kernel, so F-keys work and bindings are layout independent
([keys] in sacred_re.ini). Replaces the WASD hotkey remap and the digit
swap; W/A/S/D and the digit row no longer reach the game. Skill keys
still cast through the right mouse button. Enabled switches removed.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/mods/wasd.h

@@ -0,0 +1,8 @@
+#pragma once
+
+namespace mods::wasd {
+
+// Whether `vk` is one of the movement keys W/A/S/D.
+bool IsMovementKey(int vk);
+
+} // namespace mods::wasd