docs: bump zensical to 0.0.50 to fix search

zensical 0.0.48 shipped a regression that left the search UI hidden (fixed
upstream in 0.0.50): the built pages carried the hidden attribute on the
search components and the runtime never mounted them, so the site had no
search bar. Verified against a full 0.0.50 build: the search markup renders
without hidden, search.json is generated, and the crossref/inventory guards
and llms artifacts are unchanged.

Author: maxisbey

pyproject.toml

@@ -81,11 +81,12 @@ docs = [
     # MkDocs plugins or hooks, so the API reference (formerly gen-files +
     # literate-nav) and llms.txt (formerly a hook) are generated by the
     # standalone scripts under scripts/docs/. See scripts/docs/build.sh.
-    # 0.0.48 fixes relative/scoped cross-references for mkdocstrings-python,
-    # which the mkdocstrings config in mkdocs.yml relies on. The toolchain is
-    # pinned exactly: Zensical is pre-1.0 and the build guards key on its
-    # rendering behavior, so bumps should be deliberate.
-    "zensical==0.0.48",
+    # 0.0.48 fixed relative/scoped cross-references for mkdocstrings-python
+    # (which the mkdocstrings config in mkdocs.yml relies on) but broke
+    # search; 0.0.50 fixes it. The toolchain is pinned exactly: Zensical is
+    # pre-1.0 and the build guards key on its rendering behavior, so bumps
+    # should be deliberate.
+    "zensical==0.0.50",
     # Zensical's mkdocstrings compatibility layer targets the mkdocstrings 1.x /
     # mkdocstrings-python 2.0.5+ API (griffe 2 / griffelib); the older
     # mkdocstrings 0.30 / python 2.0.1 line renders API pages with an