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).

support.html

@@ -344,6 +344,7 @@
                                 <li><strong>Event company</strong>: Install Events and Website apps.</li>
                             </ul>
                             <p>No matter your business type, you can pick the apps that match your needs, and gradually build your Odoo system step by step.</p>
+                            <p>If you are at the very start &mdash; choosing a plan, deploying your instance, mapping your first domain &mdash; our guide on <a href="blog/posts/my-first-post.html">getting started with Odoo hosting</a> walks through it step by step.</p>
                             <p>If the question you are asking is bigger than the apps — <em>what can I use Odoo for at all, and is it right for my kind of business?</em> — we have written that answer out properly, business type by business type: <a href="what-can-i-use-odoo-for/">what you can use Odoo for</a>.</p>
                         </div>
                     </div>