* Add Docker build CI to pull requests
* Add SQLite document persistence through SQLx
* Update README to describe configuration variables
* Minor changes to README wording
* Update image size estimate listed in README
* Update frontend dependencies
* Add direct database tests and restructure code
* Clarify use of `SQLITE_URI` in Docker contexts
* Optimization: debounce user cursor updates by 20ms
This noticeably improves performance on initial page load for documents
with large histories, as previously, the user sent one cursor update message
for every past edit to the document upon joining. Now, they only send a
single cursor update at the end of the update sequence, due to the
20ms debouncing operation.
* Update NPM dependency versions
