py(deps[uv]) Revert gp-sphinx workspace pins from 0.0.1a15 back to 0.0.1a13

why: The published `gp_furo_theme-0.0.1a15-py3-none-any.whl` is broken —
28 KB, no `theme/gp-furo/static/` directory, no built CSS or JS. Every
consumer of `gp-sphinx==0.0.1a15` therefore renders an unstyled docs
site (e.g. https://libtmux.git-pull.com/, https://gp-sphinx.git-pull.com/).
Two failures chained in the v0.0.1a15 release:

1. `release.yml` ran `uv build` without first running
   `pnpm exec vite build`, so the gitignored `static/` tree was empty
   when hatchling packed the wheel.
2. Even if vite had run, `static/` is gitignored — without
   `[tool.hatch.build.targets.{sdist,wheel}.force-include]`, hatchling's
   default gitignore-aware file selection would still have dropped it.

A force-include + CI ordering fix is in flight on
`git-pull/gp-sphinx` (#27, branch `loud-fail-missing-assets`), but it
introduced a fresh regression: editable installs via `uv sync` now
fail with `FileNotFoundError: Forced include not found` when the
static dir doesn't exist on disk. The packaging design needs more
work before a16 can ship.

In the meantime, pinning every consumer back to a13 (the last version
that produced a working wheel — see https://pypi.org/project/gp-sphinx/0.0.1a13/)
unblocks docs builds across all 14 downstream sites. We chose a13
rather than a14 because a14 was also part of the broken release wave
(same packaging architecture, same risk surface).

what:
- pyproject.toml: revert all gp-sphinx workspace pins from `==0.0.1a15`
  back to `==0.0.1a13` in `[dependency-groups] dev` and `docs`.
- uv.lock: regenerated against the a13 pins; gp-sphinx workspace
  siblings (sphinx-gp-theme, sphinx-ux-autodoc-layout,
  sphinx-ux-badges, sphinx-fonts, sphinx-autodoc-typehints-gp, …)
  co-resolved back to 0.0.1a13. The upstream `furo==2025.12.19`
  dependency reappears as a transitive (gp-sphinx 0.0.1a13 still
  consumed it; a15 replaced it with the in-tree `gp-furo-theme`).

ref: https://pypi.org/project/gp-sphinx/0.0.1a13/
ref: git-pull/gp-sphinx#27

Author: tony

pyproject.toml

@@ -66,9 +66,9 @@ Repository = "https://github.com/cihai/cihai-cli"
 [dependency-groups]
 dev = [
   # Docs
-  "gp-sphinx==0.0.1a15",
-  "sphinx-autodoc-argparse==0.0.1a15",
-  "sphinx-autodoc-api-style==0.0.1a15",
+  "gp-sphinx==0.0.1a13",
+  "sphinx-autodoc-argparse==0.0.1a13",
+  "sphinx-autodoc-api-style==0.0.1a13",
   "gp-libs",
   "sphinx-autobuild",
   # Testing
@@ -93,9 +93,9 @@ dev = [
 ]
 
 docs = [
-  "gp-sphinx==0.0.1a15",
-  "sphinx-autodoc-argparse==0.0.1a15",
-  "sphinx-autodoc-api-style==0.0.1a15",
+  "gp-sphinx==0.0.1a13",
+  "sphinx-autodoc-argparse==0.0.1a13",
+  "sphinx-autodoc-api-style==0.0.1a13",
   "gp-libs",
   "sphinx-autobuild",
 ]