[notebooks] Creating a note throws a "-undefined" kea store error (accounts New note)

Summary

Creating a note from an account ("New note" in the Notes tab) throws [KEA] Can not find path "scenes.notebooks.Notebook.notebookLogic.<shortId>-undefined" in the store. notebookLogic is keyed as ${shortId}-${mode}, but the notebook side panel mounts it without passing mode, so the key resolves to <shortId>-undefined and fails to match the mounted instance. The fix is a one-line default in the key function.

Part of #68887.

Note: the fix is in the notebooks product; it surfaces from the accounts "New note" flow (accountNotebooksLogic.createNote → opens the notebook in the side panel).

Details for coding agents

Root cause

• notebookLogic key: key(({ shortId, mode }) => ${shortId}-${mode}). mode is optional (mode?: NotebookLogicMode) and only defaults to 'notebook' inside a selector, not in the key function.
• notebookPanelLogic and NotebookPanel mount the logic / render <Notebook shortId=... /> without a mode prop, so mode is undefined and the key becomes <shortId>-undefined, which doesn't match any mounted path.

Proposed fix
Default mode in the key function so it always produces a valid, matching key:

key(({ shortId, mode }) => `${shortId}-${mode ?? 'notebook'}`)

This mirrors the existing selector default. Optionally also pass an explicit mode from NotebookPanel.

References

• frontend/src/scenes/notebooks/Notebook/notebookLogic.ts:301 — key function ${shortId}-${mode}
• frontend/src/scenes/notebooks/Notebook/notebookLogic.ts:246 — mode?: NotebookLogicMode (optional)
• frontend/src/scenes/notebooks/Notebook/notebookLogic.ts:1010 — selector default props.mode ?? 'notebook'
• frontend/src/scenes/notebooks/NotebookPanel/NotebookPanel.tsx:34,95 — mounts logic / renders <Notebook> without mode
• products/customer_analytics/frontend/components/Accounts/accountNotebooksLogic.ts — createNote flow that triggers it

Start in frontend/src/scenes/notebooks/Notebook/notebookLogic.ts at the key function, then inspect NotebookPanel/NotebookPanel.tsx and the accountNotebooksLogic.ts createNote flow. Reproduce the account “New note” action and verify the notebook side panel no longer requests a -undefined store path.