refactor: rename CTaskFireBall → CTaskGirder

The only creation site for this task type is FireWeapon__Girder (0x51E350).
The "FireBall" name was a legacy RE guess; it's actually a short-lived
terrain placement task for girder/bridge objects.

Rename in ClassType enum (26 = Girder), weapon.rs comments, task-hierarchy
docs, and Ghidra labels.

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

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

@@ -33,7 +33,9 @@ pub enum ClassType {
     Cloud = 23,
     Fire = 24,
     Gas = 25,
-    FireBall = 26,
+    /// Girder placement task. Previously "FireBall" in RE sources — renamed
+    /// after confirming the only creation site is FireWeapon__Girder (0x51E350).
+    Girder = 26,
     SeaBubble = 27,
     Land = 28,
     ScoreBubble = 29,

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

@@ -557,7 +557,7 @@ unsafe fn fire_mail_mine_mole(worm: *mut CTaskWorm) {
 
 /// Girder (type 4 subtype 3) — pure Rust port of 0x51E350.
 ///
-/// Allocates a CTaskFireBall (0xA4 bytes), copies 7 DWORDs from fire_params
+/// Allocates a CTaskGirder (0xA4 bytes), copies 7 DWORDs from fire_params
 /// as constructor arguments, and calls the constructor. The constructor handles
 /// actually placing the girder on the landscape.
 ///
@@ -573,26 +573,26 @@ unsafe fn fire_girder(
     let table = SharedDataTable::from_task((*worm).as_task_ptr());
     let parent = table.lookup(0, 0x19);
 
-    // Allocate CTaskFireBall (0xA4 bytes), zero first 0x84
+    // Allocate CTaskGirder (0xA4 bytes), zero first 0x84
     let buffer = wa_malloc(0xA4);
     if buffer.is_null() {
         return;
     }
     core::ptr::write_bytes(buffer, 0, 0x84);
 
-    // CTaskFireBall::Constructor — usercall(EAX=parent) +
+    // CTaskGirder::Constructor — usercall(EAX=parent) +
     // stdcall(this, 7×fire_param DWORDs, local_struct), RET 0x24.
     // Copy 7 DWORDs from fire_params onto the stack via the naked bridge.
-    call_fireball_ctor(buffer, parent as *mut u8, fire_params, local_struct, rb(0x550890));
+    call_girder_ctor(buffer, parent as *mut u8, fire_params, local_struct, rb(0x550890));
 }
 
-/// Bridge: CTaskFireBall::Constructor — usercall(EAX=parent) +
+/// Bridge: CTaskGirder::Constructor — usercall(EAX=parent) +
 /// stdcall(this, 7 DWORDs from fire_params, local_struct), RET 0x24.
 ///
 /// The original copies 7 DWORDs from fire_params onto the stack via REP MOVSD.
 /// We replicate this by pushing them individually in reverse order.
 #[unsafe(naked)]
-unsafe extern "C" fn call_fireball_ctor(
+unsafe extern "C" fn call_girder_ctor(
     _this: *mut u8, _parent: *mut u8, _fire_params: *const WeaponFireParams,
     _local_struct: *const u8, _addr: u32,
 ) {

docs/re-notes/task-hierarchy.md

@@ -28,7 +28,7 @@ CTask (base)                    vtable: 0x669F8C    ctor: 0x5625A0
 ├── CTaskDirt                                        ctor: 0x54EDC0
 ├── CTaskFlame                                       ctor: 0x54F0F0
 ├── CTaskFire                                        ctor: 0x54F4C0
-├── CTaskFireBall                                    ctor: 0x550890
+├── CTaskGirder (was CTaskFireBall)                   ctor: 0x550890
 ├── CTaskGas                                         ctor: 0x554750
 ├── CTaskSmoke                                       ctor: 0x5551D0
 ├── CTaskCloud                                       ctor: 0x5482E0