feat: Add distinctive project avatars and remove redundant language labels

- Create 11 custom SVG avatars matching seam engineering theme
- Featured projects: claude-firefox-mcp, poly-container-mcp, my-lang,
  seambot, seamstress, rhodium-standard, poly-ssg, flatracoon-netstack
- Generic category avatars: mcp-generic, devtools-generic, zotero-generic
- Remove language labels from card footers (redundant with project names)
- Update card layout to include avatar images for featured projects
- Cleaner, more distinctive visual presentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Jonathan D.A. Jewell