v2026.6.12.1248

What changed

• Corrected the README compatibility matrix: Codex now lists /interface-design slash command support.
• Updated Codex usage docs to show both /interface-design ... and natural-language invocation.
• Updated the skill instructions so Codex treats /interface-design, $interface-design, natural language, and Claude-style legacy subcommands as equivalent action requests.
• Bumped plugin metadata to 2026.6.12.1248.

Validation

• quick_validate.py passes for the source skill.
• Plugin JSON files parse successfully.
• git diff --check HEAD passes.