## Why

The site currently renders multiple card variants (videos/podcast cards, blog post cards, etc.) with inconsistent structure and metadata placement, which makes the UI feel uneven. A standardized card layout will create a consistent UX across the website.

## What Changes

- Standardize the UI structure for all content cards across the site:
  - featured image displayed prominently on top (when available)
  - title
  - summary/excerpt, trimmed
  - meta row with date (left) and views (right) when available (`space-between`)
  - footer row showing the content source (YouTube/podcast/blog/etc.)
- Update existing card renderers/components to use the standardized structure and styling.
- Where a content source does not provide one of the fields (for example, views for blog posts), the layout MUST still render cleanly with the missing field omitted.

## Capabilities

### New Capabilities
- `card-layout-system`: Define the standard card information architecture (image/title/summary/meta/footer) and rules for optional fields so all surfaces render consistently.

### Modified Capabilities
- `social-content-aggregation`: Extend normalized content items to include an optional `summary`/`excerpt` field where available (e.g., YouTube description snippet, podcast episode summary) so non-blog cards can display a trimmed summary.
- `blog-section-surface`: Standardize blog listing cards to include the meta row (publish date and optional views) and footer source label, consistent with the global card layout system.

## Impact

- Affected code: shared card/link components (e.g., `site/src/components/ContentCard.astro`, `site/src/components/BlogPostCard.astro`) and pages that render listings (`/`, `/videos`, `/podcast`, `/blog`).
- Data model: normalized cached items may gain an optional summary field; ingestion code may need to populate it for YouTube/podcast.
- Styling: global CSS updates to ensure consistent spacing/typography and footer/meta layout.