feat(seo): wire internal links between the 17 blog posts and the pages that sell

The blog was an island: zero post→page links to hosting/upgrade/support/courses,
and only one page→post link in the whole site. Posts ranked for nothing while the
old blog host ranked for our long-tail queries.

Posts → pages (26 new in-body contextual links across 17 posts):
each post now carries one or two links to the page that answers its reader's next
question — odoo-hosting-2027, odoo-community-upgrade, support, the workshops hub,
the n8n masterclass, and the plan pricing on index.html#pricing.

Pages → posts (7 pages, one contextual link each):
index.html (OCA section), odoo-hosting-2027, odoo-community-upgrade, support,
workshops/, odoo-n8n-masterclass/, odoo-erp-automation-bootcamp/ now link into the
post that fits their own subject. The clearest miss is fixed — the
community-vs-enterprise-cost post and the odoo-community-upgrade page now link
to each other.

Anchors wrap existing sentences where the text already said the thing; four short
linking sentences were added (index OCA section, support first-steps FAQ, masterclass
lessons, bootcamp included section). No new components, no related-posts widget,
in-body anchors only. English pages only; DE/ES untouched (translator follow-up).

blog/posts/news-platform-update.html

@@ -216,7 +216,7 @@
                     <p>
                         Your control panel has been completely rebuilt for speed
                         and clarity. Key metrics &mdash; instance status,
-                        resource usage, backup history &mdash; are now front and
+                        resource usage, <a href="../../support.html">backup history</a> &mdash; are now front and
                         center. The new dashboard loads 3x faster and works
                         seamlessly on mobile.
                     </p>
@@ -236,7 +236,7 @@
                     </div>
                     <h2>AI-Powered Monitoring</h2>
                     <p>
-                        Our new monitoring system uses machine learning to
+                        Our new <a href="../../odoo-hosting-2027.html">monitoring system</a> uses machine learning to
                         detect anomalies in your instance's performance before
                         they become problems. You'll receive proactive alerts
                         with suggested remediation steps.