perf(site-wide): render-blocking /style.css on 17 pages; <main> landmark; BF footer form action

Same defect the bootcamp carried (2aa9b19), fixed site-wide in one mechanical pass.

P0 (17 pages): /style.css was deferred via media="print" onload=... -> unstyled
first paint -> a BODY layout shift. Now a normal render-blocking
<link rel="stylesheet">; the now-redundant no-JS <noscript> for style.css is
dropped. Web fonts + Font Awesome keep their legitimate deferral.
Pages: index.html, odoo-black-friday/, odoo-hosting-offers/, de/index.html,
es/index.html, odoo-hosting-2027.html (+de/+es), odoo-community-upgrade.html
(+de/+es), odoo-staging-environment/, odoo-community-ai/,
odoo-n8n-masterclass/, australia.html, workshops/, what-can-i-use-odoo-for/.

P1 (1 page): /odoo-black-friday/ footer form action mailto: -> CRM webhook
(Lighthouse is-on-https). Changed only because the page already loads a handler
for #footerContactForm (static/black-friday.js). The other 13 mailto-form pages
load no handler and are left alone on purpose (no drive-by handler copy-in).
Added the no-JS <noscript> fallback so a JS-off visitor keeps a path.

P2 (35 pages): add a single <main> landmark wrapping the primary content; top
bar and footer stay outside. Additive only, no redesign.

Guards held: bootcamp EN/DE/ES and every JS/static file untouched; Buy forms
product_id 4/17 intact; one [data-bc-seats]; ads-consent gate intact.
verify-html.py PROBLEMS 0; competitor QC 74 pre-existing, 0 added.

odoo-community-ai/index.html

@@ -23,8 +23,7 @@
       onload="this.media='all'"
     />
     <noscript><link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=Marcellus&display=swap" /></noscript>
-    <link rel="stylesheet" href="/style.css" media="print" onload="this.media='all'" />
-    <noscript><link rel="stylesheet" href="/style.css" /></noscript>
+    <link rel="stylesheet" href="/style.css" />
     <style>
       /* ---- "Odoo Community + AI agent" page (page-scoped; additive).
          Reuses the top bar, band rhythm, hero, FAQ and final-CTA treatment already
@@ -662,6 +661,7 @@
     </div>
 
     <!-- Hero -->
+    <main>
     <section class="hero oc-hero">
       <div class="hero-bg">
         <img
@@ -889,6 +889,7 @@
     </section>
 
     <!-- Footer (copied from odoo-staging-environment/; no link to this page is added anywhere) -->
+    </main>
     <footer class="footer">
       <div class="container">
         <div class="fgrid">