Pad standalone type chips, keep compound types flush

[tony]

Summary

• Fix field-list type chips (str, pathlib.Path, union members) rendering with zero horizontal padding — each type sat crammed against the edge of its chip background.
• Restore Furo's 0.2em inline padding on .field-list code.literal, which sphinx-autodoc-typehints-gp had zeroed globally.
• Preserve the tight compound rendering (list[str], dict[str, Any]) by cancelling that padding only where a chip abuts .p punctuation.

Background

typehints_gp.css zeroed padding-inline on every field-list code chip so compound annotations stayed flush — list[str], not list[ str ], since the brackets/commas live in separate <span class="p"> elements outside the chip. The side effect: standalone types (a parameter that is just str, a return of pathlib.Path) lost their chip breathing room and read as text jammed against the background edge. The earlier api-facts padding fix only covered .gp-sphinx-api-facts, so plain autodoc parameter lists on consumer sites (libtmux, django-docutils, …) kept the cramped look.

The fix

Restore the padding by default, then drop it adjacently to punctuation:

.field-list code.literal { padding-inline: 0.2em; }
.field-list code.literal:has(+ .p),
.field-list a.reference:has(+ .p) > code.literal { padding-inline-end: 0; }
.field-list .p + code.literal,
.field-list .p + a.reference > code.literal { padding-inline-start: 0; }

Linked chips wrap the <code> in <a>, so the punctuation is the anchor's sibling — the rule matches both the bare and anchored forms. Browsers without :has() degrade gracefully to padded-everywhere.

Before / After

Chip	Context	Before	After
str	standalone	flush to edges	0.2em breathing room
pathlib.Path	standalone	flush to edges	0.2em breathing room
Callable	before [	flush	flush (unchanged)
Server	inside […]	flush	flush (unchanged)

Verified live: dict[str, Any] | None keeps dict[str, Any] tight while the | None members gain padding.

Test plan

• uv run ruff check . / ruff format / uv run mypy . clean
• uv run pytest --reruns 0 — full suite green
• just build-docs succeeds; the rule is bundled into _static/css/typehints_gp.css
• Prototyped live on a production consumer page; standalone chips padded, list[str]/dict[str, Any] stay flush

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.38%. Comparing base (12483f3) to head (d0abf80).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #54   +/-   ##
=======================================
  Coverage   92.38%   92.38%           
=======================================
  Files         256      256           
  Lines       20188    20188           
=======================================
  Hits        18651    18651           
  Misses       1537     1537           

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