Add site search (Pagefind)

Client-side index generated after the Hugo build; search box in the
header, results page with a section filter.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YDRjtmAiNpo5mK5N3d7QwZ

layouts/companies/single.html

@@ -1,6 +1,6 @@
 {{ define "main" }}
 <article>
-  <p class="crumbs"><a href="{{ .Parent.RelPermalink }}">Companies</a></p>
+  <p class="crumbs" data-pagefind-ignore><a href="{{ .Parent.RelPermalink }}">Companies</a></p>
   <h1>{{ with .Params.logo }}<img class="logo" src="{{ . }}" alt="">{{ end }}{{ .Title }}</h1>
   <div class="content">{{ .Content }}</div>
   {{ with .Params.machines }}