/live feed gets rich release cards; AI excerpts replace full bodies

Changed

• The /live feed now shows rich release cards: org avatar and name, source and product identity, descriptive AI title with version tag, two-line summary, and inline media or video preview.
• Feed and collection surfaces now serve AI-generated excerpts instead of the full release body; the complete text stays on the canonical release detail page.

Fixed

• Google Sign-In and One Tap now correctly store the original-cased display email address rather than the dot-stripped lowercase form.