💄 Inter typography and a headerless sidebar

- Bundle Inter (variable, latin woff2 from Google Fonts) and use it throughout with a larger type scale — body 14px, labels 13px, hints 12px — replacing the system-font 11-13px mix - Drop the topbar (logo + name + subtitle): the sidebar's own Chrome header already identifies the extension. The ⚙ settings toggle moves into the Package slug section's header row, with the settings panel opening directly beneath it. Bumps to 1.6.0