Tourmaline share page fixes

Fixed the personality card SVG being clipped in the share page preview. The SVG now uses width="100%" with viewBox only (no fixed height) and display:block to prevent inline gaps. Removed overflow-hidden from the preview container. Switched the "View post" link after sharing from bsky.app/profile/{did}/post/{rkey} to aturi.to/{did}/{collection}/{rkey} — universal links that let the viewer choose their preferred ATProto client rather than hardcoding Bluesky's web app.