Add app icon: favicon, apple-touch icon, and top-bar logo

Generated a transparent PNG set from the source icon (a JPEG with a baked-in
checkerboard) by keying out the background on saturation — the arrow is
strongly saturated (0.47-0.68) while the grey/white background is 0.00, so
the cutout is clean. Produced static/logo.png (top-bar, natural aspect),
static/favicon.png (32px), and static/apple-touch-icon.png (180px).

Wired favicon + apple-touch links into all three page heads (feed, settings,
login) and placed the logo next to the "AgentFeed" title in the top bar.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

static/daybook.css

@@ -176,10 +176,18 @@ body {
 }
 
 .brand-link {
+  align-items: center;
   color: inherit;
+  display: flex;
+  gap: 0.45rem;
   text-decoration: none;
 }
 
+.brand-logo {
+  height: 1.6rem;
+  width: auto;
+}
+
 .brand-link:hover {
   opacity: 0.75;
 }

templates/artifacts/_topbar.html

@@ -1,6 +1,6 @@
 <header class="topbar">
   <div class="brandline">
-    <a class="brand-link" href="{% url 'feed' %}"><h1>AgentFeed</h1></a>
+    <a class="brand-link" href="{% url 'feed' %}"><img class="brand-logo" src="/static/logo.png" alt=""><h1>AgentFeed</h1></a>
   </div>
   <div class="toolbar">
     {% if topbar_toolbar %}{% include topbar_toolbar %}{% endif %}

templates/artifacts/feed.html

@@ -4,6 +4,8 @@
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>AgentFeed</title>
+  <link rel="icon" type="image/png" href="/static/favicon.png">
+  <link rel="apple-touch-icon" href="/static/apple-touch-icon.png">
   <link rel="stylesheet" href="/static/daybook.css">
   <script>
     // Set the theme before first paint so dark-mode users never see a light flash.

templates/artifacts/login.html

@@ -4,6 +4,8 @@
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>Log in — AgentFeed</title>
+  <link rel="icon" type="image/png" href="/static/favicon.png">
+  <link rel="apple-touch-icon" href="/static/apple-touch-icon.png">
   <link rel="stylesheet" href="/static/daybook.css">
   <script>
     // Set the theme before first paint so dark-mode users never see a light flash.

templates/artifacts/settings_base.html

@@ -4,6 +4,8 @@
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>Settings — AgentFeed</title>
+  <link rel="icon" type="image/png" href="/static/favicon.png">
+  <link rel="apple-touch-icon" href="/static/apple-touch-icon.png">
   <link rel="stylesheet" href="/static/daybook.css">
   <script>
     // Set the theme before first paint so dark-mode users never see a light flash.