feat(home): block native context menu and add right-click on recent projects

[srfwb]

Summary

Two changes to the right-click experience.

The Chromium/WebView native context menu (Retour, Actualiser, Inspecter…) was showing on every right-click, breaking the desktop-app feel. A one-line global listener in main.tsx now prevents it app-wide.

Right-clicking the "Projets récents" section area (the grid background, the header, or the empty space around cards) opens a custom context menu with "Nouveau projet" and "Rechercher…". Right-clicking a specific project card still shows the card's own menu (Ouvrir, Ouvrir le dossier, Renommer, Supprimer) — stopPropagation prevents the section menu from also appearing.

What changed

User-facing

• Right-click anywhere in the app no longer shows the browser's built-in menu.
• Right-click in the recent projects area (not on a card) offers "Nouveau projet" and "Rechercher…".

Internal

• src/main.tsx — global contextmenu → preventDefault() before bootstrap.
• src/home/sections/ProjectCard.tsx — onContext adds stopPropagation() so the card's menu doesn't bubble to the section handler.
• src/home/sections/RecentProjectsSection.tsx — onContextMenu on <section> opens a ContextMenu with two items. Uses the existing ContextMenu component from src/ide/tree/ContextMenu.tsx.