fix(desktop): add display language setting

[ComputelessComputer]

Separate app UI locale from the AI main language and add checks that prevent empty translated settings messages.

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Note

Medium Risk
Very large locale rollout means most new languages still show English UI strings; tests only enforce full PO coverage for ko/ja, so incorrect or missing translations elsewhere are possible.

Overview
Expands desktop UI (display) localization from a handful of locales to a large shared SUPPORTED_DISPLAY_LOCALES list aligned with spoken-language options, and wires Lingui and runtime loading to that single source of truth.

i18n plumbing now discovers catalogs via import.meta.glob instead of hand-maintained imports, and resolveDisplayLocale resolves base language codes (plus a jw → jv alias) before Intl fallback. New .po / compiled messages.ts files are added for each locale; most ship with empty msgstr and English strings in the compiled catalogs until translated.

Tests assert every supported locale loads, ko/ja PO files have no empty translations, and chat tests use the FloatingOpen shell mode. A small Japanese copy tweak is included for one settings string.

Note: PR description references separating display language from AI main language; that behavior may live in other stack commits not shown in this diff.

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This is part 3 of 3 in a stack made with GitButler:

•  3  fix(desktop): add display language setting #5369 👈
•  2  fix(desktop): round main area top corners #5371
•  1  feat(desktop): add sidebar timeline setting #5366

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Eagerly loading ~100 identical catalogs bloats bundle

Medium Severity

import.meta.glob with { eager: true } bundles and parses all ~100 locale catalog modules at startup, even though only one locale is active at a time. Previously only 3 catalogs were loaded. The new locales all contain identical English source strings (no actual translations), so the bundle now includes ~100 near-duplicate JSON blobs. Combined with i18n.load(catalogs) passing every catalog to the runtime, this significantly increases both bundle size and initialization cost for no user-visible benefit.

 

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[ComputelessComputer]

Closing this i18n branch for now. We'll redo the display-language/i18n work after the lower stack has merged.