Branding, audio navigation, and docs catalog polish

This pass brought the brand identity into the product and tightened a few rough edges across the docs experience.

What changed

• Added a reusable Logo component and brand assets, surfaced on the home page and docs browser shell, with the SDF helper updated to the new mark.
• Played navigation sounds from the click gesture and persisted the audio-unlocked state across pages, so transitions stay audible after the first interaction.
• Made the code-tabs copy button actually work, with a clipboard fallback and a transient “Copied!” label.
• Grouped and alphabetized the components catalog page into a multi-column layout instead of a flat grid.
• Lightened code block surfaces and tidied the global scrollbar and changelog card styling.

Why it matters

The docs now look and sound like a finished product: the brand is present, navigation gives feedback, and copying a snippet just works. Grouping the catalog also makes it easier to find a component as the registry grows.