refactor: move bitgrid module from display to crate root

BitGrid is a core engine type used for both rendering (display layers)
and simulation (collision masks, terrain geometry). Move it from
display::bitgrid to crate::bitgrid to reflect its fundamental role.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/openwa-core/src/address.rs

@@ -70,12 +70,12 @@ pub mod va {
         STREAMING_AUDIO_OPEN, STREAMING_AUDIO_OPEN_WAV, STREAMING_AUDIO_READ_CHUNK,
         STREAMING_AUDIO_RESET, STREAMING_AUDIO_STOP, STREAMING_AUDIO_TIMER_CALLBACK,
     };
-    pub use crate::display::base::DISPLAY_BASE_VTABLE;
-    pub use crate::display::bitgrid::{
+    pub use crate::bitgrid::{
         BitGridBaseVtable, BitGridCollisionVtable, BitGridDisplayVtable, BIT_GRID_BASE_VTABLE,
         BIT_GRID_COLLISION_VTABLE, BIT_GRID_DISPLAY_VTABLE, BIT_GRID_INIT, BLIT_SPRITE_RECT,
         DRAW_LINE_CLIPPED, DRAW_LINE_TWO_COLOR,
     };
+    pub use crate::display::base::DISPLAY_BASE_VTABLE;
     pub use crate::display::compat_renderer::{
         CompatRendererVtable, COMPAT_RENDERER_VTABLE, DDRAW8_RENDERER_VTABLE,
     };

crates/openwa-core/src/display/dd_display.rs

@@ -275,9 +275,9 @@ bind_DDDisplayVtable!(DDDisplay, vtable);
 // Ported DDDisplay vtable methods
 // =========================================================================
 
-use super::bitgrid::DisplayBitGrid;
 use super::gfx::DisplayGfx;
 use super::line_draw;
+use crate::bitgrid::DisplayBitGrid;
 
 /// Port of DDDisplay::GetDimensions (vtable slot 1, 0x56A460).
 ///

crates/openwa-core/src/display/gfx.rs

@@ -1,5 +1,5 @@
 use super::base::DisplayBase;
-use super::bitgrid::DisplayBitGrid;
+use crate::bitgrid::DisplayBitGrid;
 use core::ffi::c_void;
 
 /// DisplayGfx — full display/graphics subsystem (derived from DisplayBase).

crates/openwa-core/src/display/gradient.rs

@@ -6,7 +6,7 @@
 //! may have subtle color differences due to the tangled decompiler output.
 
 use crate::address::va;
-use crate::display::bitgrid::{BitGrid, BitGridBaseVtable};
+use crate::bitgrid::{BitGrid, BitGridBaseVtable};
 use crate::engine::ddgame::DDGame;
 use crate::rebase::rb;
 use crate::render::gfx_dir::call_gfx_find_and_load;

crates/openwa-core/src/display/mod.rs

@@ -1,5 +1,4 @@
 pub mod base;
-pub mod bitgrid;
 pub mod compat_renderer;
 pub mod dd_display;
 pub mod display_wrapper;
@@ -11,10 +10,6 @@ pub mod palette;
 pub mod sprite_blit;
 
 pub use base::{DisplayBase, DisplayBaseVtable, SpriteBufferCtrl, SpriteCacheWrapper};
-pub use bitgrid::{
-    BitGrid, BitGridBaseVtable, BitGridCollisionVtable, BitGridDisplayVtable, CollisionBitGrid,
-    DisplayBitGrid,
-};
 pub use compat_renderer::CompatRenderer;
 pub use dd_display::DDDisplay;
 pub use display_wrapper::{DDDisplayWrapper, FastcallResult};

crates/openwa-core/src/engine/ddgame.rs

@@ -2,9 +2,9 @@ use crate::audio::active_sound::ActiveSoundTable;
 use crate::audio::dssound::DSSound;
 use crate::audio::music::Music;
 use crate::audio::speech::SpeechSlotTable;
+use crate::bitgrid::{CollisionBitGrid, DisplayBitGrid};
 use crate::display::dd_display::DDDisplay;
 use crate::display::palette::Palette;
-use crate::display::{CollisionBitGrid, DisplayBitGrid};
 use crate::engine::game_info::GameInfo;
 use crate::engine::{
     CoordEntry, CoordList, RenderEntry, SoundQueueEntry, TeamArenaState, TeamIndexMap,

crates/openwa-core/src/engine/ddgame_constructor.rs

@@ -12,7 +12,7 @@ use crate::address::va;
 use crate::audio::active_sound::ActiveSoundTable;
 use crate::audio::dssound::DSSound;
 use crate::audio::music::Music;
-use crate::display::bitgrid::{BitGrid, BitGridBaseVtable, CollisionBitGrid, DisplayBitGrid};
+use crate::bitgrid::{BitGrid, BitGridBaseVtable, CollisionBitGrid, DisplayBitGrid};
 use crate::display::dd_display::DDDisplay;
 use crate::display::gradient::compute_complex_gradient;
 use crate::display::palette::Palette;

crates/openwa-core/src/lib.rs

@@ -29,6 +29,7 @@ pub use openwa_derive::FieldRegistry;
 pub mod macros;
 
 pub mod audio;
+pub mod bitgrid;
 pub mod display;
 pub mod engine;
 pub mod frontend;

crates/openwa-dll/src/replacements/ddgame_init.rs

@@ -14,7 +14,7 @@
 use crate::hook;
 use core::ffi::c_char;
 use openwa_core::address::va;
-use openwa_core::display::BitGrid;
+use openwa_core::bitgrid::BitGrid;
 use openwa_core::engine::game_state_init::{
     check_weapon_avail, init_alliance_data, init_landscape_flags, init_team_scoring,
     init_turn_state, is_super_weapon, ring_buffer_init, sprite_gfx_table_init,

crates/openwa-dll/src/replacements/display.rs

@@ -54,7 +54,7 @@ unsafe extern "thiscall" fn headless_destructor(
 /// saves pixel data to `testdata/snapshots/`. Activated by
 /// `OPENWA_CAPTURE_LINE_SNAPSHOTS=1`.
 pub unsafe fn capture_line_snapshots() {
-    use openwa_core::display::bitgrid::DisplayBitGrid;
+    use openwa_core::bitgrid::DisplayBitGrid;
     use std::fs;
     use std::io::Write;
 
@@ -273,7 +273,7 @@ pub unsafe fn capture_line_snapshots() {
 /// saves pixel output to `testdata/snapshots/`. Activated by
 /// `OPENWA_CAPTURE_BLIT_SNAPSHOTS=1`.
 pub unsafe fn capture_blit_snapshots() {
-    use openwa_core::display::bitgrid::DisplayBitGrid;
+    use openwa_core::bitgrid::DisplayBitGrid;
     use std::fs;
     use std::io::Write;
 
@@ -497,12 +497,12 @@ fn decode_gif_indexed(data: &[u8]) -> Option<IndexedImage> {
 /// `target` is the rebased runtime address of FUN_004f6910.
 #[unsafe(naked)]
 unsafe extern "cdecl" fn wa_blit_sprite_rect(
-    dst: *mut openwa_core::display::DisplayBitGrid,
+    dst: *mut openwa_core::bitgrid::DisplayBitGrid,
     dst_x: i32,
     dst_y: i32,
     width: i32,
     height: i32,
-    src: *mut openwa_core::display::DisplayBitGrid,
+    src: *mut openwa_core::bitgrid::DisplayBitGrid,
     src_x: i32,
     src_y: i32,
     color_table: u32,
@@ -584,12 +584,12 @@ unsafe extern "C" fn blit_hook_trampoline() {
 /// Handles 8bpp blend modes 0 (copy) and 1 (color table / transparency).
 /// Falls through to the original WA function for unsupported modes.
 unsafe extern "cdecl" fn blit_impl(
-    dst: *mut openwa_core::display::DisplayBitGrid,
+    dst: *mut openwa_core::bitgrid::DisplayBitGrid,
     dst_x: i32,
     dst_y: i32,
     width: i32,
     height: i32,
-    src: *mut openwa_core::display::DisplayBitGrid,
+    src: *mut openwa_core::bitgrid::DisplayBitGrid,
     src_x: i32,
     src_y: i32,
     color_table: u32,
@@ -699,12 +699,12 @@ unsafe extern "cdecl" fn blit_impl(
 ///
 /// The trampoline expects: ESI=dst, 9 stdcall params.
 unsafe fn call_original_blit(
-    dst: *mut openwa_core::display::DisplayBitGrid,
+    dst: *mut openwa_core::bitgrid::DisplayBitGrid,
     dst_x: i32,
     dst_y: i32,
     width: i32,
     height: i32,
-    src: *mut openwa_core::display::DisplayBitGrid,
+    src: *mut openwa_core::bitgrid::DisplayBitGrid,
     src_x: i32,
     src_y: i32,
     color_table: u32,
@@ -729,12 +729,12 @@ unsafe fn call_original_blit(
 /// Naked asm to call the original blit with ESI set correctly.
 #[unsafe(naked)]
 unsafe extern "cdecl" fn call_original_blit_asm(
-    _dst: *mut openwa_core::display::DisplayBitGrid,
+    _dst: *mut openwa_core::bitgrid::DisplayBitGrid,
     _dst_x: i32,
     _dst_y: i32,
     _width: i32,
     _height: i32,
-    _src: *mut openwa_core::display::DisplayBitGrid,
+    _src: *mut openwa_core::bitgrid::DisplayBitGrid,
     _src_x: i32,
     _src_y: i32,
     _color_table: u32,