test: 200 tests, 50.2% coverage — Data, I18n, Fs, Log, Embed, Runtime
New tests: Data List/ListNames/Extract, I18n with mock Translator,
Fs full surface (EnsureDir, IsDir, IsFile, Exists, List, Stat, Open,
Create, Append, ReadStream, WriteStream, Delete, DeleteAll, Rename),
Log all levels + Security + Username + Default + LogErr + LogPan,
Embed ScanAssets + GeneratePack + MountEmbed, Runtime ServiceName,
Core LogError/LogWarn/Must helpers.
Fixes: NewCommand inits flagset, New() wires Cli root command + app.
Remaining 0% (excluding CLI/App): compress, getAllFiles (internal),
Reports/appendReport (needs ErrorPanic filePath), SetOutput (trivial).
Co-Authored-By: Virgil <virgil@lethean.io>
b2d07e7883