feat: add launch module (manifest, interpolation, process exec)
- manifest: Manifest struct (files, launch config, server info), LoadManifest, LibraryFiles/ModFiles filters
- launch: Game struct (Prepare/BuildCommand/Start lifecycle)
- Prepare: download manifest, resolve Java, sync files with SHA-1, soft-delete unknown mods
- BuildCommand: classpath assembly, variable interpolation (, , etc.), authlib-injector injection
- Start: execute the assembled command
- interpolate: template replacement
- cleanupUnknownMods: moves untracked mods to mods_backup/
Co-Authored-By: OWL <noreply@anthropic.com>