## Summary
Implements the "notebook query and mutation hooks" step of the notebooks
data layer:
- `data/content/notebooks/notebook-query.ts` —
`getNotebook`/`useNotebookQuery`, wrapping the existing `getContentById`
and narrowing to `type: 'notebook'`.
- `data/content/notebooks/notebooks-infinite-query.ts` —
`useNotebooksInfiniteQuery`, a typed wrapper over
`useContentInfiniteQuery` narrowing pages to notebook rows.
- `data/content/notebooks/notebook-upsert-mutation.ts` —
`createNotebook`/`updateNotebook` + their mutation hooks, PUTting
through the existing `upsertContent`.
Write-path correctness, worked out while building the mutation hooks:
- Cell `id`s are always backend-generated, never client-supplied — a
brand-new cell has no `id` at all; an existing cell being kept/edited in
an update keeps its real id so the backend can diff it against the
previous version. `notebook-schema.ts` gains
`writableCellSchema`/`writableNotebookSchema` (ids optional per cell)
and `WritableCell`/`WritableNotebook` types, derived from `z.infer` of
those schemas rather than hand-duplicated, with only the `sql` field
re-branded per cell type via a small distributive conditional type.
- Cell SQL at this write boundary must already be
`SafeSqlFragment`/`SafeLogSqlFragment` (proven user-authored at a
save/run event handler), not `unchecked_sql` — matching the
`safe-sql-execution` skill's provenance model.
- `content-remap.ts`'s notebook `unmapSqlContentField` branch is
simplified to a passthrough: notebook writes only ever arrive already
wire-shaped via `createNotebook`/`updateNotebook`, so there's nothing
left to unmap.
Note: this was originally stacked on
`feature/notebooks-types-convergence`, but that branch merged into
`master` (#48905) while this PR was in progress, so it's rebased
directly onto `master` now.
## Test plan
- [x] `pnpm --filter studio run typecheck` passes
- [x] `pnpm --filter studio exec vitest run data/content/notebooks
data/content/content-remap.test.ts` — 38/38 passing
- [x] `pnpm --filter studio exec eslint` clean on all touched files
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added notebook listing with pagination, filtering, sorting, and
project-specific queries.
* Added notebook retrieval for viewing individual notebooks.
* Added notebook creation and editing with automatic content refresh.
* Added support for preserving cell IDs and safely handling SQL content.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->