[Windows] Desktop app spellcheck doesn't support Vietnamese (works fine on macOS)

Environment

• App: Claude desktop app (Electron-based)
• Version: 1.34493.1.0
• OS: Windows 11 Home 10.0.26200
• Vietnamese language pack installed via Windows Settings > Time & Language

Description
The built-in spellchecker in the Windows desktop app underlines all Vietnamese text as misspelled, even after installing the Vietnamese language pack in Windows Settings. There is no language selector in the spellcheck context menu (right-click on underlined word only shows suggestions/Add to dictionary/Undo/Cut/Copy/Paste — no "Languages" submenu).

On macOS, the same app correctly recognizes Vietnamese and does not flag it, since macOS Electron builds default to the native NSSpellChecker (which supports Vietnamese). On Windows, Electron falls back to its bundled Hunspell dictionaries, which historically don't include a Vietnamese dictionary, and the app does not appear to enable the Windows native Spell Checking API fallback (which does support Vietnamese).

Steps to reproduce

1. Install Vietnamese language in Windows Settings (Time & Language > Language & region)
2. Restart the Claude desktop app
3. Type Vietnamese text in any chat input box
4. All words are underlined red as misspelled; no way to add/select Vietnamese as a spellcheck language

Expected behavior
Vietnamese text should not be flagged as misspelled, either by using the OS-installed language or by enabling the Windows native spellcheck API fallback (as Chrome/Edge do for languages outside Chromium's bundled Hunspell list).

Actual behavior
All Vietnamese text is underlined red; no in-app setting exists to disable or configure spellcheck language.
(This was post using Claude)