Agent Guide on Interaction Patterns

Requested by: @bastirehm

Deliverable: A written guide, google doc.

From @bastirehm:

focused on how a flow/agent" should "behave" within GitLab, which can then lead to guidance on prompts to achieve this. This could start with a very simple list, with examples like:

1. Flows should always provide update in the item they are working on (e.g. issue or MR).
2. These updates should be in the form of a single, continuously edited comment.
3. When a flow is completed it should always post a summary into the work item. ...we should prescribe such behaviors/patterns

Needed by: ?

WIP Google Doc

Splitting from other issue: https://gitlab.com/gitlab-org/gitlab/-/issues/560002#note_2810970730