Accept installer reboot code, deterministic mod moves, and robust Steam/VDF/Proton parsing with tests

[astrovm]

Motivation

• Treat installer exit code 3010 (reboot required) as a successful install when provisioning runtimes.
• Make mod installation deterministic and safe when moving extracted files over existing targets.
• Harden Steam library detection and VDF parsing to handle whitespace-only paths and UTF-8 BOMs, and refine executable detection per game kind.
• Improve Proton directory parsing and selection logic to handle additional real-world name variants and prefer Proton installations that actually contain Wine binaries.

Description

• Added is_success_or_reboot_code helper and updated runtime installer logic to accept exit codes 0 and 3010 as success for both VC++ and .NET installers in src/external/runtime_installer.rs, plus unit tests for the helper.
• Made find_mod_root deterministic by sorting directory entries before checking for mod.ini and added remove_path and logic in move_dir_contents to remove existing targets before moving, in src/setup/common.rs, plus tests for deterministic selection and overwriting behavior.
• Enhanced Proton parsing tests in src/external/proton.rs to accept names like Proton 9, Proton 9.0 (Beta), Proton 8.0-4, and added a test to ensure directories without wine binaries are ignored when selecting Proton.
• Hardened Steam library handling in src/steam/library.rs to skip library paths that are empty/whitespace-only, restrict sonic.exe fallback to SADX only, and added tests for whitespace paths and symlinked library de-duplication (Unix-only).
• Updated VDF parser in src/steam/vdf.rs to strip a leading UTF-8 BOM before parsing and added a unit test for BOM handling.
• Minor test formatting cleanups and added/expanded unit tests across modules to cover the above changes.

Testing

• Ran the test suite with cargo test; all tests completed successfully.
• New/updated unit tests exercised the changes, including test_is_success_or_reboot_code, Proton parsing tests, test_find_mod_root_prefers_deterministic_order, test_move_dir_contents_overwrites_existing_file, Steam library tests for whitespace and symlink dedupe, and test_parse_with_utf8_bom, and all passed.

---

Codex Task