Refine semantic callout icon colors

[MaggieAppleton]

Summary

• give each existing editor callout type a dedicated semantic icon color
• apply the alias only to the trigger, Nucleo glyph, and picker leading icon
• keep titles, layout, editor behavior, and MDX/Lexical contracts unchanged

Scope

Two CSS/test files only. No new visual primitive, editor logic, product adoption, auth, permissions, or composition changes.

Stack

• depends on Add semantic badges #176

Verification

• focused tests: 18 pass
• bun test: 1,506 pass, 2 PostgreSQL skips, 0 fail
• bun run types
• bun run ci
• bun run build
• git diff --check

Component preview