docs: shorten 3 top-nav labels + bump pydata-sphinx-theme floor

Two independent low-risk nav cleanups:

1. Shorten 3 top-nav labels via toctree entry overrides in
   docs/index.rst. "Getting Started: Measuring Campaign Impact",
   "Which Analysis Method Fits Your Problem?", and "Choosing an
   Estimator" all wrap to 2 lines at 1440x900 desktop, doubling
   header height from ~64px to 128px (14% of viewport).

   Use Sphinx's `Label <target>` toctree syntax to render shorter
   labels in the nav while preserving each page's full H1 title:
   - Practitioner Guide  (was: Getting Started: Measuring Campaign Impact)
   - Decision Tree       (was: Which Analysis Method Fits Your Problem?)
   - Estimator Guide     (was: Choosing an Estimator)

   Verified locally: header height drops from 128px to 64px;
   page H1s unchanged; mobile drawer entries 1, 2, 4 reflect the
   new labels.

2. Bump pydata-sphinx-theme floor >=0.15 -> >=0.16.1 across
   pyproject.toml, .readthedocs.yaml, and
   .github/workflows/docs-tests.yml. v0.16+ shipped accessibility
   improvements. RTD attribution shows 0.17.1 already deployed,
   but 0.16.1 is the highest floor we can land while keeping
   Python 3.9 compatibility (0.17.1 requires Python>=3.10, which
   would conflict with project's requires-python>=3.9).

   On Python 3.11 (RTD/CI) pip resolves to 0.17.1 as before;
   on Python 3.9 (local dev) 0.16.1 installs.

   Verified locally: `make html SPHINXOPTS="-W"` builds clean
   with pydata-sphinx-theme 0.16.1 installed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: igerber

.github/workflows/docs-tests.yml

@@ -94,7 +94,7 @@ jobs:
         # docs/conf.py imports diff_diff via sys.path from checked-out source.
         # ipython provides the 'ipython3' Pygments lexer that nbsphinx uses
         # for notebook code cells; without it -W fires highlighting_failure.
-        run: pip install "numpy>=1.20.0" "pandas>=1.3.0" "scipy>=1.7.0" "sphinx>=6.0" "pydata-sphinx-theme>=0.15" "sphinxext-opengraph>=0.9" "sphinx-sitemap>=2.5" "nbsphinx>=0.9" "matplotlib>=3.5" "ipython>=8.0"
+        run: pip install "numpy>=1.20.0" "pandas>=1.3.0" "scipy>=1.7.0" "sphinx>=6.0" "pydata-sphinx-theme>=0.16.1" "sphinxext-opengraph>=0.9" "sphinx-sitemap>=2.5" "nbsphinx>=0.9" "matplotlib>=3.5" "ipython>=8.0"
 
       - name: Build docs with warnings as errors
         # SPHINXOPTS="-W" turns every Sphinx warning into a build failure.

.readthedocs.yaml

@@ -18,7 +18,7 @@ build:
       #
       # Keep in sync with pyproject.toml [project.dependencies]
       # and [project.optional-dependencies.docs].
-      - pip install "numpy>=1.20.0" "pandas>=1.3.0" "scipy>=1.7.0" "sphinx>=6.0" "pydata-sphinx-theme>=0.15" "sphinxext-opengraph>=0.9" "sphinx-sitemap>=2.5" "nbsphinx>=0.9" "matplotlib>=3.5" "ipython>=8.0"
+      - pip install "numpy>=1.20.0" "pandas>=1.3.0" "scipy>=1.7.0" "sphinx>=6.0" "pydata-sphinx-theme>=0.16.1" "sphinxext-opengraph>=0.9" "sphinx-sitemap>=2.5" "nbsphinx>=0.9" "matplotlib>=3.5" "ipython>=8.0"
 
 # Build documentation in the "docs/" directory with Sphinx
 sphinx:

docs/index.rst

@@ -59,16 +59,16 @@ Quick Links
    :caption: For Data Scientists
    :hidden:
 
-   practitioner_getting_started
-   practitioner_decision_tree
+   Practitioner Guide <practitioner_getting_started>
+   Decision Tree <practitioner_decision_tree>
 
 .. toctree::
    :maxdepth: 2
    :caption: Getting Started
    :hidden:
 
    quickstart
-   choosing_estimator
+   Estimator Guide <choosing_estimator>
    troubleshooting
    references
 

pyproject.toml

@@ -68,7 +68,7 @@ plotly = [
 ]
 docs = [
     "sphinx>=6.0",
-    "pydata-sphinx-theme>=0.15",
+    "pydata-sphinx-theme>=0.16.1",
     "sphinxext-opengraph>=0.9",
     "sphinx-sitemap>=2.5",
     "nbsphinx>=0.9",