Add notebook integration getting-started example

[defunctzombie]

Summary

Adds a new self-contained Jupyter notebook tutorial under jupyter_notebooks/getting_started/ that mirrors the Using the integration and Layout Management sections of the Foxglove notebook docs, so we have a runnable companion the docs and external posts can link to.

The notebook is Colab-first: dependencies are installed via %pip install "foxglove-sdk[notebook]" in the first cell, so it runs end-to-end in a fresh Colab kernel with no external assets.

What's in the notebook

jupyter_notebooks/getting_started/GettingStarted.ipynb, 12 cells:

1. Title + intro with a link back to the docs page.
2. Install — %pip install -q "foxglove-sdk[notebook]".
3. Using the integration — minimal /hello counter example mirroring the docs verbatim, including the log_time warning.
4. Logging richer data — SceneUpdateChannel cube example so the embedded viewer has something visually meaningful to render.
5. Layout management — single-panel Layout(content=MarkdownPanel(...), variables=...) example.
6. Composing panels with containers — re-logs the cube + counter, then builds a TabContainer > SplitContainer layout pairing a ThreeDeePanel (/scene) with a PlotPanel (/hello.count) so the container API is shown driving real data.
7. Where to next — links to the docs, the layouts API, the sibling data_platform notebook, and our Discord.

Per discussion, this PR intentionally does not cover:

• the "Buffer management" (nb_buffer.clear()) subsection
• the "Reloading viewer data" (viewer.refresh()) subsection
• the "load layout from JSON file" / opaque_layout workflow

Easy follow-ups if we want them later.

Other changes

• jupyter_notebooks/getting_started/README.md — folder README with front-matter (title + short description + colab_url), a Colab badge, and local-run instructions. The Colab badge uses the same https://colab.research.google.com/github/<org>/<repo>/blob/<branch>/<path> pattern as data_platform/README.md, pointing at this repo's main branch — so it works as soon as the PR merges, no separately-generated Colab share URL required.
• .utils/generate_readme.py + .utils/README_template.md.j2 — adds support for a new colab_url front-matter field so Colab links can be surfaced as a 📓 bullet in the auto-generated root README. Backwards-compatible: existing tutorials that don't set colab_url are unaffected.
• README.md — regenerated to include the new tutorial and its Colab bullet.

Testing

• ✅ Headless-executed GettingStarted.ipynb end-to-end with jupyter nbconvert --execute against foxglove-sdk[notebook]==0.22.x. Every cell runs without errors or stderr output.
• ✅ Verified all foxglove.layouts classes used (Layout, MarkdownPanel, MarkdownConfig, SplitContainer, SplitItem, TabContainer, TabItem, ThreeDeePanel, ThreeDeeConfig, PlotPanel, PlotConfig, PlotSeries, BaseRendererSceneUpdateTopicSettings, BaseRendererGridLayerSettings) exist in the installed SDK.
• ✅ Verified .utils/generate_readme.py is idempotent after the colab_url change.

The embedded Foxglove widget is an Anywidget that loads the viewer in the browser, so it doesn't render meaningfully in headless nbconvert — the validation here is that the Python in every cell completes cleanly. Real visual validation will happen when the Colab link is opened post-merge.

Rendered notebook (HTML preview)

GettingStarted.ipynb rendered to HTML

_{To show artifacts inline, enable in settings.}

  

[surbina]

Thoughts on adding a link to the Playground?

[defunctzombie]

🤔 For now I'll defer. We don't promote playground and its a very different experience than notebooks (no external libraries).