feat(site): vitrine recadrée IDE multi-projet + section Download desktop (D2)

i18n EN/FR (miroir) : hero, section « workspace » et carte feature 11 recadrés vers l'IDE multi-projet (arbre unique, onglets, dock bas), + clés de la section Download. Nouvelle section DownloadSection.vue (app de bureau : Linux/Windows/macOS, runtime embarqué, auto-update ; boutons vers la page des releases et le build depuis les sources) + entrée de nav « Download ».

Mockup WorkspaceShowcase redessiné sur le nouvel IDE : barre d'activité, arbre unifié multi-projet (api/web + worktree + session), éditeur à onglets, diff, dock terminaux à onglets, barre de statut. build:site vert, 0 tiret.

packages/site/src/i18n/en.ts

@@ -1,7 +1,8 @@
 // Messages EN : copie fidèle du dict() du design Arboretum.dc.html.
 export default {
   navFeatures: 'Features',
-  navWorkspace: 'Workspace',
+  navWorkspace: 'IDE',
+  navDownload: 'Download',
   navHow: 'How it works',
   navSecurity: 'Security',
   navFaq: 'FAQ',
@@ -9,7 +10,7 @@ export default {
   heroBadge: 'Mission control for AI coding agents',
   heroTitle: 'Mission control for your AI coding agents',
   heroSub:
-    'Run many Claude Code sessions across every git worktree, and supervise them from any device, even your phone.',
+    'A multi-project AI IDE, native and web: run many Claude Code sessions across every git worktree in one window, and supervise them from any device, even your phone.',
   getStarted: 'Get started',
   probKicker: 'The problem',
   probTitle: "Many agents across worktrees is chaos, and you're chained to one terminal.",
@@ -109,8 +110,8 @@ export default {
   copyUrl: 'Copy URL',
 
   // New feature cards (P7→P12: IDE worktree)
-  feat11Title: 'A real IDE for every worktree',
-  feat11Desc: 'Browse the file tree, edit in a full Monaco editor, and read changes as inline diffs, all in the /workspace view.',
+  feat11Title: 'A real multi-project IDE',
+  feat11Desc: 'One window for every project: a unified tree (project, worktree, session), a tabbed Monaco editor with inline diffs across projects, and Claude terminals docked below.',
   feat12Title: 'Diff & selective staging',
   feat12Desc: 'Stage, unstage or discard file by file, then commit (all or staged), amend, fetch and pull, without leaving the dashboard.',
   feat13Title: 'Remote git services',
@@ -121,10 +122,10 @@ export default {
   feat15Desc: 'A filesystem watcher streams changes the moment a file moves on disk: diffs and status update live, no refresh needed.',
 
   // Workspace IDE showcase
-  wsKicker: 'The worktree IDE',
-  wsTitle: 'A full IDE for every worktree, in the browser',
+  wsKicker: 'The multi-project IDE',
+  wsTitle: 'One IDE for all your projects, native or web',
   wsBody:
-    'Open any worktree in /workspace: a file tree on the left, a Monaco editor and inline diff in the center, and the correlated session terminal on the right. Stage changes file by file, write a commit message, push, all without leaving the page, on any device.',
+    'Open every project in a single window: a unified tree (project, worktree, Claude session) on the left, a tabbed Monaco editor with inline diffs in the center, Claude terminals docked at the bottom, and a git panel for staging, commits and push. No more one IDE window per project. Run it as a native desktop app or serve it in your browser, on any device.',
   wsEditor: 'Editor',
   wsDiff: 'Diff',
   wsFiles: 'Files',
@@ -155,4 +156,22 @@ export default {
   // Security pillar (encrypted secrets)
   sec5Title: 'Encrypted secrets',
   sec5Desc: 'Remote git credentials are encrypted at rest (AES-256-GCM) and never returned in clear by the API.',
+
+  // Desktop app (download)
+  dlKicker: 'Native desktop app',
+  dlTitle: 'Download Arboretum for your desktop',
+  dlBody:
+    'A native app for Linux, Windows and macOS. It bundles the daemon and its Node runtime, so there is nothing else to install: launch it and your multi-project IDE opens, already signed in. Tray, launch at login and auto-update included. Prefer the terminal? Keep running it in the browser with a single command.',
+  dlLinux: 'Linux',
+  dlLinuxHint: 'AppImage and .deb',
+  dlWin: 'Windows',
+  dlWinHint: 'NSIS installer and portable',
+  dlMac: 'macOS',
+  dlMacHint: 'dmg (best-effort, unsigned)',
+  dlNoNode: 'No Node install needed',
+  dlBundled: 'Daemon and runtime bundled',
+  dlAutoUpdate: 'Auto-update on Windows and Linux',
+  dlGet: 'Get the app',
+  dlSource: 'Build from source',
+  dlNote: 'Installers are published on the releases page once a desktop build is tagged. Until then, build it from source (see packages/desktop).',
 };