Improve XAML Designer through 50 persona reviews

[papanda925]

Purpose

Apply 50 simulated reviewer-persona passes to the PowerShell-only WPF/XAML designer, with special emphasis on first-time users and restricted corporate Windows environments.

Review perspectives

The review intentionally rotated through beginners, VBA/Office users, PowerShell 5.1/7 users, WPF layout/NameScope experts, security/network administrators, accessibility/high-DPI users, QA/CI maintainers, technical writers, and release reviewers.

The full simulated review record is in XamlDesigner/REVIEW_50_PERSONAS.md. These are simulated personas, not independent human reviewers.

Key improvements

• Beginner-oriented Common toolbox category and per-control descriptions
• Add button and double-click insertion so drag-and-drop is optional
• Bilingual Getting Started help plus a Japanese beginner guide
• Property type/enum hints and common-event prioritization
• Unified XAML + generated PowerShell undo/redo
• Deep subtree duplication with unique x:Name values and known ElementName reference rewriting
• Deleted-control generated handlers are disabled and archived as comments rather than lost
• Safe Preview blocks risky loose-XAML/custom CLR construction and automatic external resource loading
• Last known-good preview is preserved when a new preview fails
• UTF-8 BOM save for Windows PowerShell 5.1/Japanese compatibility, with legacy read fallback
• Two-file save staging/backups/rollback to reduce inconsistent XAML/PS1 pairs
• Automatic STA relaunch without bypassing execution policy
• Accessibility labels and smaller/high-DPI-friendlier minimum window size
• Expanded regression tests
• Windows CI now exercises both Windows PowerShell 5.1 and PowerShell 7

Release gate

Do not merge until repository validation, core behavior, generated-code tests, and full designer startup smoke tests pass in both PowerShell 5.1 and PowerShell 7.