feat: Add search functionality

# Feature Request

## Motivation Behind Feature
it's hard to find things in the site without search functionality

## Feature Description
a search box where you enter a text and returns the pages where the text you searched appear

## Alternatives or Workarounds
we had algolia search but was not working and was removed, so we might try to figure out how to add it back or add an alternative thing

The issue does not name any files, tests, or entry points. Start by inspecting the documentation site's existing search-related code and the history of the removed Algolia integration, then define an implementation approach; done means a search box returns the documentation pages containing the entered text.

Written by the indexing model from the issue text.