Site: search over the documentation (#60)

A search page whose index is the page itself: one item for each page and
each heading of the guide, the how-tos, the FAQ and the developer docs,
written by Zola from the pages' own content. A small script filters and
ranks them as you type. Nothing is fetched, so the Content-Security-Policy
needs nothing new; without JavaScript the page is a list of every heading.

The navigation gets a link, and the documentation's index pages a box that
is a plain form to /search/?q=. The devlog is not searched.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

site/content/search.md

@@ -0,0 +1,5 @@
++++
+title = "Search"
+description = "Find a word in the user guide, the how-tos, the questions and answers, and the developer docs."
+template = "search.html"
++++