[Story]: PM Buddy — arrival steps

[LinseCed]

User Story

As a PM in the buddy's team mode, I want to write, reorder and remove my project's arrival steps — accounts, access, a working setup — so new people know what has to be true before they can work. Nothing changes until I confirm it.

Context & Motivation

• Type: Functional (agent actions on the PM surface)
• Parent epic: 05 EPIC - Agent Orchestration & Workflow Actions #54 (05 EPIC – Agent Orchestration & Workflow Actions)
• Teams: team:backend
• Concept: pm-buddy-concept.md
• Builds on: [Story]: PM Buddy — run a managed project from the buddy #312 (team mode, stored proposals, mounting by area)

The critical piece of this story: the arrival service takes an optional project, and no project means the global default list for everyone. Team mode must always pass the managed project, so a PM can never change the global list through the buddy.

In Scope

• List, create (several at once), update, reorder and delete arrival steps of the managed project
• Show which steps the system can check itself

Acceptance Criteria

• A manager can create several steps in one confirm
• A step the system can check is shown and stored as system-confirmed, whatever was asked
• The global default list cannot be read or changed from team mode
• Deleting a step is marked destructive
• Every change is a proposal until confirmed

Technical Notes

• No frontend or AI work: tool labels fall back to a generic label, and the persona only describes mounted tools.

Sub-Tasks (by team)

• Backend — team-mode actions for arrival steps (Team-mode actions: arrival steps sprintstart-backend#227)