Fix move to folder picker

[jsgrrchg]

Summary

• Adds a compact Move to Folder picker with folder search and / Root support.
• Extends contextual move actions to notes, PDFs, generic files, folders, and mixed selections.
• Shares move execution between context-menu actions and drag/drop so each item type keeps its correct backend path.

Root Cause

The context menu only modeled the move flow for Markdown notes, even though drag/drop and the backend already supported moving PDFs and generic vault files.

Validation

• npm test -- src/features/vault/FileTree.test.tsx src/features/vault/fileTreeMoves.test.ts
• npm run lint -- src/features/vault/FileTree.tsx src/features/vault/FileTree.test.tsx src/features/vault/fileTreeMoves.ts src/features/vault/fileTreeMoves.test.ts

Closes #42

[jsgrrchg]

Speed is an issue, takes half a second for the menu to appear.

[jsgrrchg]

Looks ready.