feat(bootcamp): move the live seat-count line immediately below the hero

The [data-bc-seats] line lived in the Price-and-booking section; the user wants it
just under the hero. Moved (not copied) on EN/DE/ES — one element per page, the same
/static/bootcamp-availability.js, every string unchanged ("x of 6 seats available" /
"x von 6 Plätzen frei" / "x de 6 plazas disponibles").

Also adds a page-scoped :disabled style for the Buy buttons so a sold-out cohort's
disabled buttons actually read as disabled (rule: zero is honest — the buy must not
look open). Buy forms untouched: still post product_id 17.

odoo-erp-automation-bootcamp/index.html

@@ -192,6 +192,14 @@
       form[action$="/shop/post_basket"] .btn {
         line-height: inherit;
       }
+      /* At 0 seats /static/bootcamp-availability.js disables these Buy buttons; make the
+         disabled state read as disabled — quiet dimming in the page's own CI, never an
+         alert banner. */
+      form[action$="/shop/post_basket"] .btn:disabled,
+      form[action$="/shop/post_basket"] .btn[aria-disabled="true"] {
+        opacity: 0.5;
+        cursor: not-allowed;
+      }
 
       /* Grids — auto-fit so no breakpoint is needed */
       .bc-list {
@@ -671,6 +679,13 @@
       </div>
     </section>
 
+    <!-- Live remaining-seat count, immediately below the hero. One seat element only on
+         the page; /static/bootcamp-availability.js fills it from the availability webhook
+         and leaves it empty+hidden if that fetch fails. -->
+    <div class="container">
+      <p class="bc-note bc-seats" data-bc-seats hidden></p>
+    </div>
+
     <!-- From zero to a running ERP -->
     <section class="section-light">
       <div class="container">
@@ -859,7 +874,6 @@
         <h2 class="section-title">Price and booking</h2>
         <p class="bc-price">The programme costs USD 595.00 for all ten sessions.</p>
         <p class="bc-note"><strong>Limited to 6 participants</strong> &mdash; the cohort is capped, so the instructor can work through your own setup.</p>
-        <p class="bc-note bc-seats" data-bc-seats hidden></p>
         <p class="bc-note">A seat can be <strong>transferred at any time</strong>, and <strong>cancelled up to two weeks before</strong> the first session on 21 January 2027.</p>
         <p class="bc-lead">
           Covers the full programme: ten live sessions, one year of hosted Odoo Community Edition, the