Add trusted solution downloads and asset inventory cards

[adilei]

Summary

• require an explicit trust acknowledgement before enabling solution ZIP downloads
• explain that community solutions are not Microsoft products and may create or modify Power Platform resources
• link download supportability guidance to SUPPORT.md
• replace cramped graph thumbnails with a consistent workflow, agent, tool, MCP, and skill asset inventory
• show counts only for included asset types while retaining muted empty slots for stable scanning
• rename rendered page titles and social link metadata to Copilot Studio Gallery

Validation

• confirmed a gated download has no href, is aria-disabled, and cannot navigate before acknowledgement
• confirmed checking the acknowledgement enables and downloads the expected solution ZIP
• verified five asset slots and zero horizontal overflow at 320px and 390px
• visually reviewed the complete three-column card gallery
• ran npm run astro -- check
• ran npm run build