TUI: add nested store create/edit flow from profile form

[rmanibus]

Summary

Allow the profile form to create or edit a store without forcing the user to leave profile creation.

Motivation

The current TUI profile modal only allows choosing an existing store. That creates a dead end when the needed store has not been configured yet.

UX direction

• Keep the profile modal as the primary flow.
• Make the Store field a selector with existing stores plus contextual management entries.
• Support a nested store modal from the profile form.

Proposed interaction

1. In the profile modal, the Store field cycles through existing stores.
2. The selector also includes + Create store.
3. Selecting + Create store and confirming opens a store modal.
4. Saving the new store returns to the profile modal with the new store selected.
5. When an existing store is selected, the user can also open Edit store for that store.
6. Editing returns to the profile modal and keeps the edited store selected.

Scope

• Create store from the profile modal
• Edit currently selected store from the profile modal
• Return to the profile modal after save/cancel
• Keep delete/remove out of scope for this slice

Notes

• This is intentionally narrower than the broader store inventory view in TUI: add store inventory and status view #223.
• The store modal should be type-driven, similar to the smarter source input in the profile modal.
• Editing should clearly communicate that a store may be shared by multiple profiles.

Related: #223