* Basic filesystem navigation
* Add file picker modal
* Implement autosave when dirty and show the status
* Add hompage link in the session view
* Improve file picker and use in both places
* Move session list to homepage
* Some refactoring
* Show import messages if any
* Fix and extend tests
* Show a message when there are no sessions running
* Rename import to fork and make that clear in notebook name
* Fix old route
* Show info when no file is connected to the given session
* Show runtime type next to filename
* Show button for joining session when a running path is selected
* Move modal components to SessionLive namespace
* Add FileGuard to lock files used for notebook persistence
* Use radio for specifying persistence type
* Don't lock nil path
* Simplify FileGuard implementation
* Test notebook persistence
* Fix typo
* Further simplify FileGuard
* Improve file listing
* Don't show parent dir when there's a basename being typed
* Add path component tests
* Define session data structure and some operations
* Make code evaluation request async, so that we don't need an intermediary process
* Simplify id typespecs
* Make operation application composable
* Keep a separate evaluation queue per section and actually support concurrent evaluation
* Small fixes
* Validate queued cell type and set evaluation timestamp
* Apply review suggestions
* Add tests
* Store evaluating_cell_id instead of section status
* Add dynamic supervisor for managing evaluator processes
* Some fixes
* Refactor operation application
* Upon cell deletion mark dependent cells as stale
