Add StyLua for consistent code formatting

[refaim]

Summary

Add StyLua to enforce consistent code formatting across the project.

Motivation

The project has ~6.4k lines of Lua across 23 files. A formatter would eliminate style discussions and keep formatting consistent as the codebase evolves.

Plan

1. Add a .stylua.toml configured to match the current code style (indentation, line width, etc.) to minimize churn
2. Run initial formatting pass as a dedicated commit
3. Add that commit's SHA to .git-blame-ignore-revs to keep git blame useful

Notes

• The initial formatting commit will produce a large diff — this is expected and should be a one-time cost
• StyLua supports Lua 5.1 which is what WoW uses