[needs testing] Add commit and publish dialog

[magland]

Changes

This PR adds a confirmation dialog when committing metadata changes with three options:

• Cancel: Discard the commit action
• Commit Only: Commit metadata to draft without publishing
• Commit and Publish (Recommended): Commit metadata and immediately publish a new version

Implementation details:

1. Proxy Server - Added endpoint to handle publish requests to DANDI API
2. API Utils - Added publishDandiset() function for calling the publish endpoint
3. Commit Dialog - New CommitConfirmDialog component with three action buttons
4. Commit Button - Updated to show dialog before committing, handles both commit-only and commit-and-publish flows

The 'Commit and Publish' option is styled as the preferred/default action.

Note: This needs testing before merging, particularly:

• Verify the publish endpoint works correctly
• Test both commit-only and commit-and-publish flows
• Confirm error handling works properly

[magland]

@bendichter I haven't tested this.
It's on the preview site: https://dandiset-metadata-assistant.surge.sh/dandiset-metadata-assistant

[h-mayorquin]

As soon as I entered one of my datasets I got "pending changes already":

Looking at the diff more in detail it seems that it somehow comparing cached data from another of my datasets...

[magland]

@h-mayorquin That bug has been fixed in #43

[h-mayorquin]

I tried this again. I clicked on "commit" and got "Failed to Fetch"

Also, should we really recommend “Commit and publish”? What is the logic behind this? Should the behavior be different when the dataset is still in draft?

I think that for drafts this option should not be available. We might want to have a separate Publish button that only works after a commit has already been completed. This would avoid errors when a user clicks Publish by mistake, since publishing is irreversible.