refactor: extract WeaponFireParams sub-struct from WeaponEntry

The region at WeaponEntry+0x3C onward is passed as a pointer to all
fire sub-functions. Extract it as WeaponFireParams (0x194 bytes),
embedded in WeaponEntry. Internal layout still unknown but the struct
boundary is now explicit.

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

crates/openwa-core/src/game/weapon.rs

@@ -135,14 +135,23 @@ pub struct WeaponEntry {
     pub fire_subtype_34: i32,
     /// +0x38: Fire subtype for weapon types 1 (projectile) and 2 (rope).
     pub fire_subtype_38: i32,
-    /// +0x3C: Weapon fire params start. Address of this field is passed
-    /// to fire sub-functions as the params base pointer.
-    pub fire_params_start: u32,
-    /// +0x40-0x1CF: Unknown fields.
-    pub _unknown_40: [u8; 0x1D0 - 0x40],
+    /// +0x3C: Fire parameters sub-structure. Pointer to this field is passed
+    /// to fire sub-functions (PlacedExplosive, Projectile, CreateWeaponProjectile, etc.).
+    pub fire_params: WeaponFireParams,
 }
 const _: () = assert!(core::mem::size_of::<WeaponEntry>() == 0x1D0);
 
+/// Weapon fire parameters — embedded at WeaponEntry+0x3C.
+///
+/// Pointer to this struct is passed to all fire dispatch sub-functions.
+/// Internal layout is mostly unknown (0x194 bytes).
+#[repr(C)]
+pub struct WeaponFireParams {
+    /// +0x00 (WeaponEntry+0x3C): First param DWORD.
+    pub _data: [u8; 0x1D0 - 0x3C],
+}
+const _: () = assert!(core::mem::size_of::<WeaponFireParams>() == 0x1D0 - 0x3C);
+
 /// Weapon table — flat array of 71 entries, no header.
 ///
 /// Allocated by `InitWeaponTable` (0x53CAB0), stored at DDGame+0x510.

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

@@ -196,7 +196,7 @@ unsafe extern "cdecl" fn fire_weapon_impl(
     let weapon_type = (*entry).fire_type;
     let subtype_34 = (*entry).fire_subtype_34;
     let subtype_38 = (*entry).fire_subtype_38;
-    let fire_params = &raw const (*entry).fire_params_start as u32;
+    let fire_params = &raw const (*entry).fire_params as u32;
     let w = worm as u32;
 
     // Log weapon fire