Add favicon and make profile picture editable per page

- Favicon: emoji-based inline SVG (🍯), the old /images/favicon/favicon.ico
  reference never resolved to an actual file.
- Profile picture (the circular image at the top) is now a per-page
  "profile_image" field editable in /admin, instead of a hardcoded
  URL in the template.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

templates/page.html

@@ -4,7 +4,7 @@
   <meta charset="UTF-8" />
   <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
   <title>Honey | Links</title>
-  <link rel="icon" type="image/x-icon" href="/images/favicon/favicon.ico">
+  <link rel="icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🍯</text></svg>">
   <link href="https://fonts.googleapis.com/css2?family=Inter:wght@400;600&display=swap" rel="stylesheet"/>
   <link rel="stylesheet" href="{{ url_for('static', filename='styles.css') }}">
 </head>
@@ -22,7 +22,7 @@
   </div>
 
   <!-- Content on top -->
-  <img src="https://c.tenor.com/rfib5QqA0ncAAAAd/tenor.gif" alt="Profile Picture" class="profile-pic" />
+  {% if page.profile_image %}<img src="{{ page.profile_image }}" alt="Profile Picture" class="profile-pic" />{% endif %}
   <h1 class="fade-in">{{ page.title }}</h1>
   {% if page.subtitle %}<p class="bio fade-in">{{ page.subtitle }}</p>{% endif %}
   {% if page.subtitle2 %}<p class="bio2 fade-in">{{ page.subtitle2 }}</p>{% endif %}