Add contributor profiles and improve graph previews

[adilei]

Summary

• add individual contributor profile pages and link contributor identities throughout the gallery
• improve agent, MCP, skill, tool, and connector topology visuals in thumbnails and interactive graphs
• add deterministic non-overlapping agent lanes, directional workflow routing, and reliable graph hydration
• use the official Copilot Studio and MCP product marks
• refine tag filtering, hero copy, action contrast, and graph controls

Validation

• npm test -- --run
• npm run check
• npm run build
• Playwright overlap, direction, toolbar, and zoom checks across representative agent and workflow pages