Windows Desktop App: Full-width CJK numbers and Unicode block characters render incorrectly

Bug Description

On the Windows Desktop App (Microsoft Store version), certain Unicode characters render incorrectly (mojibake / garbled text):

1. Full-width CJK numbers (U+FF10-FF19: ０１２３４５６７８９) — displayed as garbled/corrupted characters
2. Unicode block elements (U+2580-259F: ▐▛███▜▌ ▝▜█████▛▘) used in the Claude ASCII logo on the start screen — displayed as broken/misaligned glyphs

Half-width numbers (0-9) and standard Japanese text (hiragana, katakana, kanji) render correctly.

Environment

• App: Claude Desktop App (Windows Store / MSIX package)
• OS: Windows 11 Home 10.0.26200
• Package path: AppData\Local\Packages\Claude_pzs8sxrjxfjjc
• Display: 2560x1440, scale factor 1x
• Installed fonts: Cascadia Code, Consolas, Yu Gothic, BIZ UDGothic, MS Gothic all present
• Locale: ja-JP

Steps to Reproduce

1. Open the Claude Desktop App on Windows
2. Open Claude Code (terminal) within the app
3. Type or observe full-width numbers: ０１２３４５６７８９
4. Observe the Claude logo on the start screen

Expected Behavior

• Full-width numbers should render correctly
• The Claude ASCII art logo should render with proper Unicode block element characters

Actual Behavior

• Full-width numbers appear garbled/corrupted
• The ASCII art logo block characters (▐▛▜▌▝) are misaligned and broken

Notes

• The built-in terminal in the Desktop App does not expose font configuration settings, so users cannot work around this by switching to a font with better Unicode coverage.
• Half-width characters and standard CJK text render fine — the issue is specifically with full-width numerals and Unicode block drawing characters.
• File I/O is unaffected (files written by Claude Code contain correct UTF-8 data). This is purely a rendering/display issue.

Workaround

• Use half-width numbers (0-9) instead of full-width (０-９)
• Run claude CLI in Windows Terminal (where font is configurable) instead of the Desktop App's built-in terminal