🎨 assets: add a logo, Annotated[T, metadata] with a check

[nstarman]

is_annotated had no logo. This gives it one: the shape of Annotated[T, x], checked. Square brackets surround a type, drawn as a teal block, and its metadata, drawn as a purple flag. A yellow badge with a tick asks the question this package answers. It uses GalacticDynamics' navy, teal 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: 661 bytes and sharp at any size. The script writes the SVG text directly, so the default needs no dependencies.
• Geometry: the brackets, type block, flag and badge 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 is_annotated has docs. Nothing references it yet.

Checked: prek passes on the new files, 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 (a3ac02f) to head (68d3aab).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #56   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            1         1           
  Lines            6         6           
=========================================
  Hits             6         6           

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