[2.1 Docs] UI & Admin: profile page, preferences/persona, custom properties #583

Document 2.1 profile, preferences and custom-properties UI additions.

Scope: OpenMetadata (OSS) docs only. Collate/AI-mode features are out of scope for this repo.

Work

• Per-user preferences and tenant default (user_preferences). PRs: OpenMetadata#31188, #31488 — Already documented in v2.1.x-SNAPSHOT/deployment/upgrade/breaking-changes/ui-and-customization.mdx (App Mode, per-user preferences API). The profile Preferences panel is AI shell only.
• Persona App Layout card (default App Mode + default landing page). PR: OpenMetadata#34189 — Already documented in v2.0.x and v2.1.x-SNAPSHOT (customizable-landing-page.mdx, from Docs: Persona landing page, profile sample, and request compression updates for 2.0.4/2.0.5 #577).
• Custom Properties tab redesign. PR: OpenMetadata#34042 — Done in v2.1.x-SNAPSHOT/how-to-guides/guide-for-data-users/custom.mdx (search, sort, cards, add/edit window). Needs a new screenshot of the redesigned tab.
  (TagClassBase.getAutoClassificationComponent), so it is Collate-only. The same PR's classification Edit action is already in manage-classification.mdx.

UI images still needed (OSS): redesigned Custom Properties tab, and the add/edit window.