HUD: centre the taskbar, move the portrait/health panel to the right edge

New mods/hud: while a HUD window renders, screen-space vertices passed to
D3D7 DrawPrimitive/DrawIndexedPrimitive are shifted by dx; while it handles
an event, the UI event point (category 5, +0x48) is shifted by -dx. Applied
to cUI_Taskbar2 (centred) and cUI_Mercenary (portrait + health, right edge).
3D belt items line up without help (their projection is screen-centred).
re::AttachRuntimeHook hooks functions only known at runtime (COM methods).

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

src/mods/hud.h

@@ -0,0 +1,8 @@
+#pragma once
+
+namespace mods::hud {
+
+// Installs the Direct3D device hooks the HUD layout needs (once per device).
+void OnDevice(void* device);
+
+} // namespace mods::hud