Improve "Details" tooling.

[evalstate]

• Include full Model/Dataset Card README in prompts ✅
• Combine Model Details and Dataset Details tool ✅
• Expose as prompts. ✅
• Make inclusion of README in tool results configurable through Settings. ✅
• Update huggingface.co/settings/mcp to allow configuration, migrate to new tools.

To try this new tool add [?|&]mix=hub_repo_details_readme to the URL for the version with README inclusion, [?|&] mix=hub_repo_details for the version without.