Add clickable reference badges and improve UI layout

- Add clickable badges for backlinks and references that trigger query string searches
- Improve toggle checkbox layout with better styling
- Add description block styling with scrollable container
- Update results styling with bordered cards and shadows
- Add favicon support across pages
- Enhance .env loading with logging for debugging

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

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

static/frequency.html

@@ -4,6 +4,7 @@
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
     <title>Term Frequency Explorer</title>
+    <link rel="icon" href="/static/favicon.png" type="image/png" />
     <link rel="stylesheet" href="/static/style.css" />
     <style>
       #chart {
@@ -65,4 +66,3 @@
     <script src="/static/frequency.js"></script>
   </body>
 </html>
-