Agent UI v0.4.8

Agent UI v0.4.8 is a patch release that refreshes the Agent standards ecosystem after Agent Context became a current published standard.

Highlights

• Adds Agent Context to the current standards table and boundary map.
• Removes Agent Context from the future-candidate list.
• Adds Agent Context to README related-standard links.
• Updates LLM entrypoints so AI clients can discover Agent Context.
• Adds version snapshot pages for v0.4.8.