Add inventory record type prompt to notebook templating [sc-16131]

[emmavdh]

What and why?

Adds an inventory record type step to notebook generation (make notebook / e2e-notebook.ipynb) so newly authored notebooks can target Model, Agent, Use Case, Tool, or a custom free-text type.

• Separate prompt alongside the existing role/document-type selection
• Defaults to Model on empty input
• Fills {record-type} placeholders in install and next-steps mini-templates

Shortcut: https://app.shortcut.com/validmind/story/16131

How to test

1. From repo root: make notebook (or run notebooks/templates/e2e-notebook.ipynb)
2. After role/document type, confirm the record-type prompt offers 1–4, custom 5 / free text, and Enter → Model
3. Choose e.g. Agent with install+initialize; open the generated notebook and confirm registration/next-steps text says Agent (no leftover {record-type})
4. Repeat with a custom value and confirm substitution

What needs special review?

Wording of {record-type} substitutions in install/next-steps mini-templates (UI labels like Register {record-type}).

Dependencies, breaking changes, and deployment notes

None. Existing published notebooks are unchanged; only the generator and mini-templates used for new notebooks are affected.

Release notes

Internal contributor tooling for notebook authoring.

Checklist

• What and why
• Screenshots or videos (Frontend)
• How to test
• What needs special review
• Dependencies, breaking changes, and deployment notes
• Labels applied
• PR linked to Shortcut
• Unit tests added (Backend)
• Tested locally
• Documentation updated (if required)
• Environment variable additions/changes documented (if required)