Build: lazy-load LocalHistoryDialog from FilesExplorer to silence chunk warning and actually defer it

[NicolaasGrobler]

Problem

src/components/ui/LocalHistoryDialog.tsx is imported two ways:

• Statically from src/components/explorer/FilesExplorer.tsx:4
• Dynamically (via lazy()) from src/components/layout/MainContent.tsx:36

Rollup's static import wins, so the lazy() in MainContent has zero effect — the dialog ends up in FilesExplorer's eager chunk and is loaded as part of the cold-start path anyway. Vite warns about this on every npm run build:

LocalHistoryDialog.tsx is dynamically imported by … MainContent.tsx but also statically imported by … FilesExplorer.tsx, dynamic import will not move module into another chunk.

Fix

Convert FilesExplorer.tsx's static import to a lazy() + Suspense wrapper that matches the pattern in MainContent.tsx. Once both sites are lazy, Rollup splits the dialog into its own chunk and the warning disappears.

Acceptance

• npm run build no longer emits the "dynamic import will not move module into another chunk" warning for LocalHistoryDialog.tsx.
• The dialog still opens correctly from both Files Explorer and the editor's local-history button.