feat(desktop): window translucency slider in Appearance settings (#45086)

A see-through-window control (0–100, off by default) that maps to the
native window opacity via setOpacity — the desktop shows through the whole
window, the same effect as the Windows shift-scroll trick. macOS + Windows;
a no-op on Linux (no runtime window opacity).

Renderer owns the value (persisted, nanostore) and mirrors it to the main
process over IPC; main persists it to translucency.json so a cold launch
applies it at window creation before the renderer reports in.

apps/desktop/src/i18n/en.ts

@@ -296,6 +296,8 @@ export const en: Translations = {
       colorModeDesc: 'Pick a fixed mode or let Hermes follow your system setting.',
       toolViewTitle: 'Tool Call Display',
       toolViewDesc: 'Product hides raw tool payloads; Technical shows full input/output.',
+      translucencyTitle: 'Window Translucency',
+      translucencyDesc: 'See your desktop through the whole window. macOS and Windows only.',
       product: 'Product',
       productDesc: 'Human-friendly tool activity with concise summaries.',
       technical: 'Technical',

apps/desktop/src/i18n/ja.ts

@@ -210,6 +210,8 @@ export const ja = defineLocale({
       colorModeDesc: '固定モードを選ぶか、Hermes をシステム設定に合わせます。',
       toolViewTitle: 'ツール呼び出しの表示',
       toolViewDesc: 'プロダクト表示は生のツールペイロードを隠し、テクニカル表示は入出力をすべて表示します。',
+      translucencyTitle: 'ウィンドウの透過',
+      translucencyDesc: 'ウィンドウ全体を透過させてデスクトップを表示します。macOS と Windows のみ。',
       product: 'プロダクト',
       productDesc: '読みやすいツール活動と簡潔な要約を表示します。',
       technical: 'テクニカル',

apps/desktop/src/i18n/types.ts

@@ -213,6 +213,8 @@ export interface Translations {
       colorModeDesc: string
       toolViewTitle: string
       toolViewDesc: string
+      translucencyTitle: string
+      translucencyDesc: string
       product: string
       productDesc: string
       technical: string

apps/desktop/src/i18n/zh-hant.ts

@@ -204,6 +204,8 @@ export const zhHant = defineLocale({
       colorModeDesc: '選擇固定模式，或讓 Hermes 跟隨系統設定。',
       toolViewTitle: '工具呼叫顯示',
       toolViewDesc: '產品模式會隱藏原始工具 payload；技術模式會顯示完整輸入/輸出。',
+      translucencyTitle: '視窗透明',
+      translucencyDesc: '讓整個視窗透出桌面。僅支援 macOS 與 Windows。',
       product: '產品',
       productDesc: '易讀的工具活動與精簡摘要。',
       technical: '技術',

apps/desktop/src/i18n/zh.ts

@@ -291,6 +291,8 @@ export const zh: Translations = {
       colorModeDesc: '选择固定模式，或让 Hermes 跟随系统设置。',
       toolViewTitle: '工具调用显示',
       toolViewDesc: '产品模式隐藏原始工具数据；技术模式显示完整输入/输出。',
+      translucencyTitle: '窗口透明',
+      translucencyDesc: '让整个窗口透出桌面。仅支持 macOS 和 Windows。',
       product: '产品',
       productDesc: '易读的工具活动与简洁摘要。',
       technical: '技术',