3145

Added

• Skin Theme Variants — skins can now declare named theme variants; users can select a per-skin theme persisted in UserDefaults.
• Skin Validator — ZIP-based pre-import validation with a results sheet showing severity-categorised findings and fix suggestions.

Changed

• debug field optional — info.json no longer requires a debug key; missing value defaults to false so legacy skins import without error.
• Validator debug finding — missing debug key is now a .warning (not .error) consistent with the optional decoding behaviour.
• Validation result title — sheet title now reads "Imported with Warnings" for warning-only results, "Validation Issues" for errors, and "Skin Valid" only when clean.