Align message specializations with card actions

[VolkerChristian]

Summary

• move steering, update, and final-answer specializations to the right side of card headers
• render all specializations at normal weight immediately before Copy
• remove separator glyphs and preserve canonical status/identity colors in native and WebUI
• update behavior/design documentation and regression coverage

Verification

• native codexui-conversation-cards-test passed
• native codex-ui target built successfully
• WebUI test suite passed: 78/78