Refactor excerpt and description handling for consistency (#76)

- Enable page_excerpts in _config.yml so Jekyll auto-generates
  page.excerpt for pages (not just posts)
- resource.html: move description from body to header hgroup subtitle;
  resources use description in front matter, not excerpt, so the old
  header check was dead code
- project.html: remove dead {% if page.description %} body block;
  projects use excerpt (shown in header), description was never set
- jsonld.html: fix meetup Event description, which was always empty
  since meetups have no description front matter field; fall back to
  page content stripped and truncated to 50 words

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: alexwolson

_config.yml

@@ -13,6 +13,7 @@ github_username: civictechto
 
 timezone: America/Toronto
 future: true
+page_excerpts: true
 
 include:
   - _pages

_includes/jsonld.html

@@ -71,11 +71,12 @@
     "url": {{ page.url | absolute_url | jsonify }}
 
   {% elsif page_tags contains "type/meetup" %}
+    {% assign meetup_description = page.description | default: page.content | strip_html | strip_newlines | truncatewords: 50 %}
     "@type": "Event",
     "name": {{ page.title | jsonify }},
     "startDate": "{{ page.date }}",
     "endDate": "{{ page.date }}",
-    "description": {{ page.description | strip_html | strip_newlines | jsonify }},
+    "description": {{ meetup_description | jsonify }},
     {% if page.venue %}
       "location": {
         "@type": "Place",

_layouts/project.html

@@ -45,9 +45,6 @@ <h1>{{ page.title }}</h1>
     <div class="main-with-sidebar">
       <div class="main-content">
         <section class="project-description">
-          {% if page.description %}
-          <p>{{ page.description }}</p>
-          {% endif %}
           {{ content }}
         </section>
       </div>

_layouts/resource.html

@@ -14,16 +14,13 @@
     <header>
       <hgroup>
         <h1>{{ page.title }}</h1>
-        {% if page.excerpt %}
-          <p>{{ page.excerpt }}</p>
+        {% if page.description %}
+          <p>{{ page.description }}</p>
         {% endif %}
       </hgroup>
     </header>
 
     <section class="resource-details">
-      {% if page.description %}
-        <p>{{ page.description }}</p>
-      {% endif %}
 
       {% if page.website %}
         <p>