feat(picker): browse Vault and entity docs in document pickers

The Add Documents modal and the new-tabular-review picker only listed
regular projects (GET /projects excludes is_vault/is_entity), so reviews
couldn't select Vault or entity documents through the UI.

- useDirectoryData: extract a shared fetchDirectoryData() that also
  resolves /projects/vault-info and /projects/entities, loads their
  documents best-effort, and appends them after the regular projects.
  GET /projects itself is unchanged.
- AddNewTRModal: reuse fetchDirectoryData() instead of its own
  duplicate directory fetch.
- backend GET /projects/:projectId: allow org-wide read of vault/entity
  projects (aligns with checkProjectAccess) so non-owners can browse
  their documents.
- backend listAccessibleProjectIds: include vault/entity project ids so
  filterAccessibleDocumentIds and review scoping accept their documents
  for every authenticated user, not just the owner.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>