Watch mode: auto-rebuild on dependency file change

[Oaklight]

Problem

Current 'auto-compile' triggers only on saving the active file. If you edit intro.tex then switch to main.tex and save, fine — but editing an included file and waiting for it to be the saved one is awkward. Also images / .bib updates outside the editor don't trigger anything.

Proposed

• Server-side file watcher on project root
• Debounced rebuild when any file under the main file's dependency graph changes
• Toggle in settings (default off to avoid surprise rebuilds)

Notes

Use watchfiles or stdlib equivalent; respect .gitignore to skip noise.

Priority: P3