Remove remaining data-field-type attributes from demo site

- Complete transition to zero-config approach
- Container expansion now handles content type detection automatically
- No manual field type declarations needed with div.insertr containers

demo-site/about.html

@@ -33,7 +33,7 @@
     <section class="services">
         <div class="container">
             <h2 class="insertr">Our Story</h2>
-            <div class="insertr" data-field-type="markdown">
+            <div class="insertr">
                 <p>Founded in 2020, Acme Consulting emerged from a simple observation: small businesses needed access to the same high-quality strategic advice that large corporations receive, but in a format that was accessible, affordable, and actionable.</p>
                 
                 <p>Our founders, with combined experience of over 30 years in business strategy, operations, and technology, recognized that the traditional consulting model wasn't serving the needs of growing businesses. We set out to change that.</p>
@@ -51,21 +51,21 @@
             
             <div class="services-grid" style="margin-top: 3rem;">
                 <div class="service-card">
-                    <div class="insertr" data-field-type="markdown">
+                    <div class="insertr">
                         <h3>Sarah Chen</h3>
                         <p><strong>Founder & CEO</strong></p>
                         <p>Former <strong>McKinsey consultant</strong> with 15 years of experience in strategy and operations. MBA from Stanford.</p>
                     </div>
                 </div>
                 <div class="service-card">
-                    <div class="insertr" data-field-type="markdown">
+                    <div class="insertr">
                         <h3>Michael Rodriguez</h3>
                         <p><strong>Head of Operations</strong></p>
                         <p>20 years in manufacturing and supply chain optimization. Expert in <strong>lean methodologies</strong> and process improvement.</p>
                     </div>
                 </div>
                 <div class="service-card">
-                    <div class="insertr" data-field-type="markdown">
+                    <div class="insertr">
                         <h3>Emma Thompson</h3>
                         <p><strong>Digital Strategy Lead</strong></p>
                         <p>Former tech startup founder turned consultant. Specializes in <em>digital transformation</em> and technology adoption.</p>