Feature: Add incremental deploys

Description

If you want to add a single file to a site, you currently have to

1. Fetch all files from a site with /sites/{site_id}/files
2. Add the new file to the file list
3. Send the full file list with POST /sites/{siteId}/deploys
4. Deploy the all required files with PUT /deploys/{deployId}/files/{path}

This process is not only error prone, it also leads to a lot of unnecessary network traffic, especially for long file list. The proposed feature aims at improving and simplifying this process.

Feature

At a minimum steps 1. + 2. are not needed with a new version of /sites/{siteId}/deploys. This new version could have the following signature:

PATCH /sites/{siteId}/deploys
Parameters: sha keys of all files that should be added to the existing files
Return: same as before: list of required files for upload and a new deployId

Step number 4 would still be necessary, if an upload is required.

Alternatives

Maybe it is possible to avoid steps 1.-3. altogether with an improved version of PUT /deploys/{deployId}/files/{path}, theerby simplifying the process even further.

Note: This is a feature request for the API core functionality and not a spec issue.

Start by reviewing the existing deploy endpoints and their API definitions, especially POST /sites/{siteId}/deploys and PUT /deploys/{deployId}/files/{path}. Clarify whether the intended change is the proposed PATCH endpoint or an improved upload flow, then define the required request, response, and compatibility behavior before implementation.