feat: implement article search with PostgreSQL full-text search

- Configure Wagtail database search backend with English search config
- Add django.contrib.postgres to INSTALLED_APPS for full PG FTS support
- Expand ArticlePage.search_fields: body_text (excl. code blocks),
  AutocompleteField(title), RelatedFields(tags), FilterFields
- Add search view at /search/?q= with query guards (strip, max 200 chars,
  empty/whitespace handling) and pagination preserving query param
- Replace nav Subscribe CTA with compact search box (desktop + mobile)
- Add search box to article index page alongside category/tag filters
- Create search results template reusing article_card component
- Add update_index to deploy entrypoint for automated reindexing
- Update existing tests for nav change, add comprehensive search tests

Closes #41

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

templates/blog/search_results.html

@@ -0,0 +1,59 @@
+{% extends 'base.html' %}
+{% block title %}{% if query %}Search: {{ query }}{% else %}Search{% endif %} | No Hype AI{% endblock %}
+{% block head_meta %}
+  <meta name="robots" content="noindex" />
+{% endblock %}
+{% block content %}
+
+<!-- Page Header -->
+<div class="py-8 md:py-12 border-b border-zinc-200 dark:border-zinc-800 mb-12">
+  <h1 class="font-display font-black text-4xl md:text-6xl mb-6">Search</h1>
+  <form action="{% url 'search' %}" method="get" role="search" class="relative w-full md:w-96">
+    <svg class="absolute left-3 top-1/2 -translate-y-1/2 w-5 h-5 text-zinc-400" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor"><path stroke-linecap="round" stroke-linejoin="round" d="m21 21-5.197-5.197m0 0A7.5 7.5 0 1 0 5.196 5.196a7.5 7.5 0 0 0 10.607 10.607Z" /></svg>
+    <input type="search" name="q" value="{{ query }}" placeholder="Search articles..." autofocus
+      class="w-full bg-brand-surfaceLight dark:bg-brand-surfaceDark border border-zinc-300 dark:border-zinc-700 pl-11 pr-4 py-3 font-mono text-sm focus:outline-none focus:border-brand-cyan dark:focus:border-brand-cyan focus:ring-1 focus:ring-brand-cyan transition-shadow" />
+  </form>
+  {% if query %}
+    <p class="mt-4 font-mono text-sm text-zinc-500">
+      {% if results %}{{ results.paginator.count }} result{{ results.paginator.count|pluralize }} for "{{ query }}"{% else %}No results for "{{ query }}"{% endif %}
+    </p>
+  {% endif %}
+</div>
+
+{% if results %}
+<!-- Results -->
+<div class="space-y-8">
+  {% for article in results %}
+    {% include 'components/article_card.html' with article=article %}
+  {% endfor %}
+</div>
+
+<!-- Pagination -->
+{% if results.has_previous or results.has_next %}
+<nav aria-label="Pagination" class="mt-12 flex justify-center items-center gap-4 font-mono text-sm">
+  {% if results.has_previous %}
+    <a href="?q={{ query|urlencode }}&page={{ results.previous_page_number }}" class="px-6 py-3 border border-zinc-300 dark:border-zinc-700 hover:bg-zinc-100 dark:hover:bg-zinc-800 transition-colors">← Previous</a>
+  {% endif %}
+  <span class="text-zinc-500">Page {{ results.number }} of {{ paginator.num_pages }}</span>
+  {% if results.has_next %}
+    <a href="?q={{ query|urlencode }}&page={{ results.next_page_number }}" class="px-6 py-3 border border-zinc-300 dark:border-zinc-700 hover:bg-zinc-100 dark:hover:bg-zinc-800 transition-colors">Next →</a>
+  {% endif %}
+</nav>
+{% endif %}
+
+{% elif query %}
+<!-- No Results -->
+<div class="py-16 text-center">
+  <svg class="w-16 h-16 text-zinc-300 dark:text-zinc-700 mx-auto mb-6" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1" stroke="currentColor"><path stroke-linecap="round" stroke-linejoin="round" d="m21 21-5.197-5.197m0 0A7.5 7.5 0 1 0 5.196 5.196a7.5 7.5 0 0 0 10.607 10.607Z" /></svg>
+  <p class="font-mono text-zinc-500 mb-2">No articles match your search.</p>
+  <p class="font-mono text-sm text-zinc-400">Try different keywords or browse <a href="/articles/" class="text-brand-cyan hover:underline">all articles</a>.</p>
+</div>
+{% else %}
+<!-- Empty State -->
+<div class="py-16 text-center">
+  <svg class="w-16 h-16 text-zinc-300 dark:text-zinc-700 mx-auto mb-6" xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1" stroke="currentColor"><path stroke-linecap="round" stroke-linejoin="round" d="m21 21-5.197-5.197m0 0A7.5 7.5 0 1 0 5.196 5.196a7.5 7.5 0 0 0 10.607 10.607Z" /></svg>
+  <p class="font-mono text-zinc-500">Enter a search term to find articles.</p>
+</div>
+{% endif %}
+
+{% endblock %}