Store test world files as a single compressed zip to reduce LFS bandwidth

[Copilot]

85 .wld test fixtures were consuming 476 MB of git LFS storage. Replace them with a single world-files.zip (88 MB, 81% reduction) using maximum zlib compression, tracked via LFS.

Changes

• world-files.zip — all 85 .wld files packed at compression level 9; added to LFS via .gitattributes
• ModuleInit.cs — pre-test extraction: world-files.zip is unpacked to WorldFiles/ before any test runs; thread-safe with path traversal guard
• TEdit.Tests.csproj — copies world-files.zip to output instead of individual .wld files
• .gitattributes — removed global *.wld LFS filter; added scoped src/TEdit.Tests/WorldFiles/*.zip LFS filter
• .gitignore — allowlist exception for src/TEdit.Tests/WorldFiles/*.zip; ignore extracted *.wld files so they don't get accidentally committed
• All 85 .wld files removed from git tracking (git rm --cached)

Extraction logic

private static void ExtractWorldFiles()
{
    var worldFilesDir = Path.Combine(AppContext.BaseDirectory, "WorldFiles");
    var zipPath = Path.Combine(worldFilesDir, "world-files.zip");
    if (!File.Exists(zipPath)) return;

    lock (_extractLock)
    {
        using var archive = ZipFile.OpenRead(zipPath);
        foreach (var entry in archive.Entries)
        {
            // ... path traversal check, then:
            if (!File.Exists(destinationPath))
                entry.ExtractToFile(destinationPath);
        }
    }
}

Extraction is idempotent — already-present .wld files are skipped, so subsequent test runs pay no extraction cost.