fix: use *mut u8 in TeamArenaRef, add team_header_mut

TeamArenaRef.base was *const u8 but team_header_mut() cast it to
*mut, which is unsound. Change base to *mut u8 so all mutable
access goes through legitimate mutable pointers.

blocks() now returns *mut TeamBlock. team_header_mut() no longer
needs a const-to-mut cast.

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

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

@@ -1898,7 +1898,7 @@ impl TeamArenaState {
 #[repr(transparent)]
 #[derive(Clone, Copy)]
 pub struct TeamArenaRef {
-    base: *const u8,
+    base: *mut u8,
 }
 
 impl TeamArenaRef {
@@ -1909,7 +1909,7 @@ impl TeamArenaRef {
     #[inline]
     pub unsafe fn from_raw(base: u32) -> Self {
         Self {
-            base: base as *const u8,
+            base: base as *mut u8,
         }
     }
 
@@ -1927,8 +1927,8 @@ impl TeamArenaRef {
 
     /// Get pointer to the TeamBlock array base.
     #[inline]
-    pub unsafe fn blocks(&self) -> *const TeamBlock {
-        self.base.sub(offsets::ARENA_TO_BLOCKS) as *const TeamBlock
+    pub unsafe fn blocks(&self) -> *mut TeamBlock {
+        self.base.sub(offsets::ARENA_TO_BLOCKS) as *mut TeamBlock
     }
 
     /// Get the team header (metadata) for a team.
@@ -1940,6 +1940,12 @@ impl TeamArenaRef {
         &(*self.blocks().add(team_idx + 1)).header.team
     }
 
+    /// Get a mutable team header for a team.
+    #[inline]
+    pub unsafe fn team_header_mut(&self, team_idx: usize) -> &mut TeamHeader {
+        &mut (*self.blocks().add(team_idx + 1)).header.team
+    }
+
     /// Get a playable worm entry by 1-indexed worm number (1..=8).
     ///
     /// Uses raw pointer arithmetic matching the original WA code:

crates/openwa-wormkit/src/replacements/weapon.rs

@@ -400,7 +400,6 @@ unsafe fn fire_weapon_special(
 /// In game_version > 0x1C: toggles (set/clear). Otherwise: always sets.
 unsafe fn fire_skip_go(worm: *const CTaskWorm, entry: *const WeaponEntry) {
     use openwa_core::engine::ddgame::TeamArenaRef;
-    use openwa_core::engine::ddgame::TeamHeader;
     use openwa_core::engine::DDGame;
 
     let ddgame = (*worm).base.base.ddgame as *mut DDGame;
@@ -412,13 +411,13 @@ unsafe fn fire_skip_go(worm: *const CTaskWorm, entry: *const WeaponEntry) {
 
     let arena_ptr = &raw mut (*ddgame).team_arena as u32;
     let arena = TeamArenaRef::from_raw(arena_ptr);
-    let header = arena.team_header(team_index) as *const TeamHeader as *mut TeamHeader;
-    let flags = (*header).turn_action_flags;
+    let header = arena.team_header_mut(team_index);
+    let flags = header.turn_action_flags;
 
     if game_version > 0x1C && (flags & bit) != 0 {
-        (*header).turn_action_flags = flags & !bit;
+        header.turn_action_flags = flags & !bit;
     } else {
-        (*header).turn_action_flags = flags | bit;
+        header.turn_action_flags = flags | bit;
     }
 }