Full File Extensions 1.1.3

• Removed all forced CSS declarations and replaced them with specific, plugin-owned File Explorer selectors.
• Extension shading now uses opacity: 0.5.
• Extension font size, line height, weight, family, and spacing inherit from the filename.
• Moved build.mjs, main.ts, and test.cjs to the repository root.
• npm run build now runs node build.mjs.
• Filename splitting, truncation, tooltips, dotfiles, extensionless files, settings, and rename behavior remain consistent with 1.1.2.