Document sessionConsoleViewModels as intentional client state

[ExtraToast]

What to build

Write down that one Pinia store is staying, and why.

The console view-model store is genuine derived client state, not cached server state, so it is correctly a store. Recording that makes it an intentional choice rather than something a future reader assumes was missed — and gives the next person a worked example of where the line between the query cache and Pinia actually falls.

Acceptance criteria

• The store's role is documented where a contributor to this application will find it
• The reasoning distinguishes derived client state from cached server state
• The guidance is concrete enough to classify the next new store

Blocked by

• Convert the server-state half of the workspaces store to Query