Fix combatlog player name resolution: stdcall ABI for GetObjectPtr

The old code called GetObjectByGUID (0x464870) as __fastcall with the
GUID in ECX/EDX, but the function is actually __stdcall with the u64
GUID on the stack. This ABI mismatch caused a crash.

Switched to perfboost's two-step approach with correct conventions:
  1. GetObjectPtr (0x464870) — __stdcall(u64 guid) → object ptr
  2. CGUnit_C::GetUnitName (0x609210) — __thiscall(ECX=unit, 0) → char*

Also added ESI/EDI/EBX clobber barrier in the EnableChatLogging detour
and copy name to stack buffer before log write.

src/combatlog/offsets.zig

@@ -0,0 +1,46 @@
+//! Address constants for combat log session rotation.
+
+// =============================================================================
+// Combat log path and state
+// =============================================================================
+
+/// Path table pointer — .data section (RW), points to "Logs\WoWCombatLog.txt" string.
+/// Index 0 (0x0084360c) = chat log, index 1 (0x00843610) = combat log.
+/// Overwriting the u32 at this address redirects where the combat log file is created.
+pub const COMBAT_LOG_PATH_PTR: usize = 0x00843610;
+
+/// Runtime combat log buffer handle (log_handles[1], BSS).
+/// Non-zero when combat logging is active. Read to check if we can write log lines.
+pub const COMBAT_LOG_HANDLE: usize = 0x00b50544;
+
+// =============================================================================
+// Log writing
+// =============================================================================
+
+/// WriteFormattedLogMessage — __cdecl(handle: u32, fmt: [*:0]const u8, ...).
+/// Writes a timestamped, formatted line to the log buffer. Auto-flushes at 48KB.
+pub const FN_WRITE_FMT_LOG_MSG: usize = 0x0065ac20;
+
+// =============================================================================
+// Combat log enable
+// =============================================================================
+
+/// EnableChatLogging — __fastcall(ECX=lua_State, EDX=index).
+/// index 0=chat, 1=combat. Called by LoggingCombat()/LoggingChat() Lua functions.
+/// Reads path from path_table[index] and opens log file on first enable.
+pub const FN_ENABLE_CHAT_LOGGING: usize = 0x0049fe50;
+
+// =============================================================================
+// Player identity (shared with markers module)
+// =============================================================================
+
+/// GetPlayerGUID — __fastcall(), no params, returns EAX(low):EDX(high).
+pub const FN_GET_PLAYER_GUID: usize = 0x00468550;
+
+/// GetObjectPtr — __stdcall(u64 guid) → object ptr in EAX.
+/// GUID is pushed on the stack as 8 bytes. (perfboost: 0x464870)
+pub const FN_GET_OBJECT_PTR: usize = 0x00464870;
+
+/// CGUnit_C::GetUnitName — __thiscall(ECX=unit_ptr, stack: flag=0) → char* in EAX.
+/// (perfboost: 0x609210)
+pub const FN_GET_UNIT_NAME: usize = 0x00609210;