🎨 assets: add a logo, [0]

[nstarman]

zeroth had no logo. This gives it one: [0], index zero between square brackets, for the first element of any iterable. It uses GalacticDynamics' navy and purple.

docs/_static/make_logo.py writes it:

uv run docs/_static/make_logo.py                     # docs/_static/favicon.svg
uv run docs/_static/make_logo.py --size 2048 big.png # a PNG, at any size

• SVG by default: 335 bytes and sharp at any size. The script writes the SVG text directly, so the default needs no dependencies.
• Geometry: the brackets and the zero are each one constant at the top of the script.
• PNG on request: rendered with resvg-py, declared in the script's PEP 723 header, so uv run fetches it.
• Location: docs/_static/, as in the other GalacticDynamics packages, ready for when zeroth has docs. Nothing references it yet.

Checked:

• The pre-commit hooks pass on the new files. The mypy hook is limited to src/, so it doesn't apply.
• Re-running the script reproduces the file, and it stays readable at 32 px.

Part of giving the GalacticDynamics packages scripted logos.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (97b80f3) to head (a46c3f3).

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #52   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines            6         6           
=========================================
  Hits             6         6           

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