Lay out the overlay panels in a fixed 3-column scheme

Panels used to Begin at cascade positions, so they overlapped and clipped. A new
apply_panel_layout() in app_chrome positions/sizes each panel from the main
viewport work area (ImGuiCond_FirstUseEver, still movable): Injection left column
full height (room for hook diagnostics), Controllers/Video/Audio stacked in the
center column, Log right edge full height (max room for the log stream). Added a
"View -> Reset layout" menu item (request_layout_reset / apply_layout_end_frame
re-apply the defaults once via ImGuiCond_Always). Each panel now calls
apply_panel_layout(Panel::X) instead of its own ad-hoc SetNextWindowPos/Size.

Verified live: captured the host overlay -- Injection (left, full height),
Controllers/Video/Audio (center stack), Log (right, full height), no overlap among
the panels. x64 build + ctest green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

host/src/main.cpp

@@ -191,6 +191,7 @@ int run()
 		{
 			draw_overlay_hidden_hint(ImGui::GetTime() - overlay_hidden_at);
 		}
+		coop::apply_layout_end_frame(); // clear the one-shot "Reset layout" force
 
 		RECT client = {};
 		GetClientRect(window.hwnd(), &client);