Support pre-uploading files to a session before it starts

[redhat-ship-help]

Summary

Currently, adding files to a session can only occur after the pod has been created. Users cannot seed a new session with uploaded files before it starts.

Problem

There is no way to upload files to a session prior to pod creation. The upload functionality depends on an existing pod to insert files into, which means users must:

1. Start a session
2. Wait for the pod to be created
3. Only then upload/add files

This creates a suboptimal workflow when a user wants to begin a session with specific files already present.

Proposed Solution

Enable pre-uploading files to Minio/S3 before the session starts. The session's init container phase should then seed the uploaded files into the workspace when the pod starts up. This way users can:

1. Upload files to Minio/S3 storage
2. Start a new session
3. Have those files automatically available when the session pod initializes

Context

Discussed in #forum-ambient-code-platform.

[github-actions]

🤖 Amber is working on this issue. A PR will be created shortly with the ambient-code:managed label.

[github-actions]

🤖 Amber session completed (phase: Running). View session