docs: render DataFrame cell outputs as text, not the HTML widget

myst-nb prefers a cell's `_repr_html_` over its text repr. A datafusion
DataFrame's HTML repr is a Jupyter-oriented widget — inline styles plus an
injected <script> — that renders at the wrong width in the docs theme.

Set nb_mime_priority_overrides so the html builder prefers text/plain. The
35 cells that end in a bare DataFrame now show the same readable ASCII
table the old IPython directive produced, with no per-cell `.show()` edits
and no dependence on the package-generated HTML staying theme-compatible.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: timsaucer

docs/source/conf.py

@@ -75,6 +75,13 @@
 nb_execution_timeout = 120
 nb_execution_raise_on_error = True
 
+# Prefer the plain-text repr of a cell's last expression over its rich
+# `_repr_html_`. A DataFrame's HTML repr is a self-contained widget (inline
+# styles + an injected <script>) built for Jupyter; in the docs theme it
+# renders at the wrong width. The text repr is the readable table the old
+# IPython directive showed and is stable across datafusion versions.
+nb_mime_priority_overrides = [("html", "text/plain", 0)]
+
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ["_templates"]