Comment hooks and reliability fixes

This release adds commenting to the App SDK, with new React hooks for reading and writing comments on your documents. It also improves reliability across document saving, permission fetching, and subscription handling.

The React SDK now includes hooks for working with comments on your documents. Use useComments and useCommentThreads to read comments, and useCommentActions to create them. Like the SDK's other data hooks, the read hooks are live by default, so comment threads stay up to date as they change. Each comment targets a document and a specific field, and comment messages are stored as Portable Text.

For the full set of React hooks, see the App SDK hooks documentation.

• Saving no longer stops after you edit a document with emoji or accented characters.
• The SDK now retries transient failures when fetching a dataset's permissions.
• The SDK now cleans up subscription IDs when reverting outgoing transactions.
• ResourceProvider now accepts null as a fallback.