A4: Integrate TOML parser #124

Summary

Add a TOML parser to the engine for reading server.toml, game mode definitions, mission files, and module configuration.

Requirements

• Parse server.toml with [server], [game], [data], [gamespy] sections
• Parse [[modules]] array entries with name, dll/lua, and [modules.config]
• Parse game mode TOML files with [mode], [[handlers]]
• Parse mission TOML files with [mission], [mission.overrides], [[handlers]]
• Expose config values to modules via config_string(), config_int(), config_float(), config_bool()

Options

• toml-c -- small, single-file
• Hand-rolled minimal parser (our config is relatively simple)

Reference

• TOML Reference -- All TOML formats
• Data Format Guide

Acceptance Criteria

• TOML parser integrated and building
• server.toml loading replaces hardcoded CLI globals
• Module config sections accessible via engine API
• Unit tests for TOML parsing

Blocks: #122 (module loader), #120