feat(search): Add complete Search UI with API and web interface

Implements full search functionality for StarPunk v1.1.0.

Search API Endpoint (/api/search):
- GET endpoint with query parameter (q) validation
- Pagination via limit (default 20, max 100) and offset parameters
- JSON response with results count and formatted search results
- Authentication-aware: anonymous users see published notes only
- Graceful handling of FTS5 unavailability (503 error)
- Proper error responses for missing/empty queries

Search Web Interface (/search):
- HTML search results page with Bootstrap-inspired styling
- Search form with HTML5 validation (minlength=2, maxlength=100)
- Results display with title, excerpt, date, and links
- Empty state for no results
- Error state for FTS5 unavailability
- Simple pagination (Next/Previous navigation)

Navigation Integration:
- Added search box to site navigation in base.html
- Preserves query parameter on results page
- Responsive design with emoji search icon
- Accessible with proper ARIA labels

FTS Index Population:
- Added startup check in __init__.py for empty FTS index
- Automatic rebuild from existing notes on first run
- Graceful degradation if population fails
- Logging for troubleshooting

Security Features:
- XSS prevention: HTML in search results properly escaped
- Safe highlighting: FTS5 <mark> tags preserved, user content escaped
- Query validation: empty queries rejected, length limits enforced
- SQL injection prevention via FTS5 query parser
- Authentication filtering: unpublished notes hidden from anonymous users

Testing:
- Added 41 comprehensive tests across 3 test files
- test_search_api.py: 12 tests for API endpoint validation
- test_search_integration.py: 17 tests for UI rendering and integration
- test_search_security.py: 12 tests for XSS, SQL injection, auth filtering
- All tests passing with no regressions

Implementation follows architect specifications from:
- docs/architecture/v1.1.0-validation-report.md
- docs/architecture/v1.1.0-feature-architecture.md
- docs/decisions/ADR-034-full-text-search.md

Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

templates/search.html

@@ -0,0 +1,114 @@
+{% extends "base.html" %}
+
+{% block title %}{% if query %}Search: {{ query }}{% else %}Search{% endif %} - StarPunk{% endblock %}
+
+{% block content %}
+<div class="search-container">
+  <!-- Search Header -->
+  <div class="search-header">
+    <h2>Search Results</h2>
+    {% if query %}
+    <p class="note-meta">
+      Found {{ results|length }} result{{ 's' if results|length != 1 else '' }}
+      for "<strong>{{ query }}</strong>"
+    </p>
+    {% endif %}
+  </div>
+
+  <!-- Search Form -->
+  <div class="search-form-container" style="background: var(--color-bg-alt); padding: var(--spacing-md); border-radius: var(--border-radius); margin-bottom: var(--spacing-lg);">
+    <form action="/search" method="get" role="search">
+      <div class="form-group" style="margin-bottom: 0;">
+        <div style="display: flex; gap: var(--spacing-sm);">
+          <input
+            type="search"
+            name="q"
+            placeholder="Enter search terms..."
+            value="{{ query }}"
+            minlength="2"
+            maxlength="100"
+            required
+            autofocus
+            style="flex: 1;"
+          >
+          <button type="submit" class="button button-primary">Search</button>
+        </div>
+      </div>
+    </form>
+  </div>
+
+  <!-- Results -->
+  {% if query %}
+    {% if error %}
+      <!-- Error state (if search unavailable) -->
+      <div class="flash flash-warning" role="alert">
+        <h3 style="margin-bottom: var(--spacing-sm);">Search Unavailable</h3>
+        <p>{{ error }}</p>
+        <p style="margin-bottom: 0; margin-top: var(--spacing-sm);">Full-text search is temporarily unavailable. Please try again later.</p>
+      </div>
+    {% elif results %}
+      <div class="search-results">
+        {% for result in results %}
+        <article class="search-result" style="margin-bottom: var(--spacing-lg); padding-bottom: var(--spacing-lg); border-bottom: 1px solid var(--color-border);">
+          <h3 style="margin-bottom: var(--spacing-sm);">
+            <a href="{{ result.url }}">{{ result.title }}</a>
+          </h3>
+          <div class="search-excerpt" style="margin-bottom: var(--spacing-sm);">
+            <!-- Excerpt with highlighted terms (safe because we control the <mark> tags) -->
+            <p style="margin-bottom: 0;">{{ result.excerpt|safe }}</p>
+          </div>
+          <div class="note-meta">
+            <time datetime="{{ result.published_at }}">
+              {{ result.published_at[:10] }}
+            </time>
+          </div>
+        </article>
+        {% endfor %}
+      </div>
+
+      <!-- Pagination (if more than limit results possible) -->
+      {% if results|length == limit %}
+      <nav aria-label="Search pagination" style="margin-top: var(--spacing-lg);">
+        <div style="display: flex; gap: var(--spacing-md); justify-content: center;">
+          {% if offset > 0 %}
+          <a class="button button-secondary" href="/search?q={{ query|urlencode }}&offset={{ [0, offset - limit]|max }}">
+            Previous
+          </a>
+          {% endif %}
+          <a class="button button-secondary" href="/search?q={{ query|urlencode }}&offset={{ offset + limit }}">
+            Next
+          </a>
+        </div>
+      </nav>
+      {% endif %}
+    {% else %}
+      <!-- No results -->
+      <div class="flash flash-info" role="alert">
+        <h3 style="margin-bottom: var(--spacing-sm);">No results found</h3>
+        <p>Your search for "<strong>{{ query }}</strong>" didn't match any notes.</p>
+        <p style="margin-bottom: 0; margin-top: var(--spacing-sm);">Try different keywords or check your spelling.</p>
+      </div>
+    {% endif %}
+  {% else %}
+    <!-- No query yet -->
+    <div class="empty-state">
+      <p style="font-size: 3rem; margin-bottom: var(--spacing-md);">🔍</p>
+      <p>Enter search terms above to find notes</p>
+    </div>
+  {% endif %}
+</div>
+
+<style>
+/* Search-specific styles */
+mark {
+  background-color: #ffeb3b;
+  padding: 0.125rem 0.25rem;
+  border-radius: 2px;
+  font-weight: 600;
+}
+
+.search-result:last-child {
+  border-bottom: none;
+}
+</style>
+{% endblock %}