Add subtle sponsor line: header strip + footer, tracked UTM

index.html

@@ -34,6 +34,12 @@
   <a class="nav-cta" href="#ask">Ask a question</a>
 </header>
 
+<aside class="sponsor" aria-label="Hosting sponsor">
+  <p><span class="sponsor-label">Help us</span>
+     <a href="https://ODOO4projects.com/?utm_source=oc-guy.com&amp;utm_medium=website&amp;utm_campaign=homepage" target="_blank" rel="noopener sponsored">Odoo Community hosting</a>
+     <span class="sponsor-note">— our hosting sponsor</span></p>
+</aside>
+
 <main id="top">
 
   <section class="lead" id="welcome" aria-labelledby="lead-title">
@@ -194,6 +200,8 @@
   <div class="foot-cols">
     <p class="foot-note">Odoo Community advocate. Written by Oliver Arnold, 安雷威 —
       no partner programme, no licences sold.</p>
+    <p class="sponsor-foot"><span class="sponsor-label">Help us</span>
+      <a href="https://ODOO4projects.com/?utm_source=oc-guy.com&amp;utm_medium=website&amp;utm_campaign=homepage" target="_blank" rel="noopener sponsored">Odoo Community hosting</a> — our hosting sponsor</p>
     <nav class="foot-links" aria-label="Elsewhere">
       <a href="https://www.odoo.com/documentation" target="_blank" rel="noopener">Documentation</a>
       <a href="https://github.com/OCA" target="_blank" rel="noopener">OCA modules</a>