feat: dynamic logo from synced assets + SVG favicon

Logo handler now checks Hub-synced assets first, falling back to
embedded SVG. Added SVG favicon to layout and catchall templates.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/web/templates/catchall.html

@@ -5,6 +5,7 @@
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>{{if .AppName}}{{.AppName}} — {{end}}felhom.eu</title>
+<link rel="icon" type="image/svg+xml" href="{{.ControllerURL}}/static/felhom-logo.svg">
 <style>
 *{margin:0;padding:0;box-sizing:border-box}
 body{background:#0d1117;color:#e6edf3;font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;min-height:100vh;display:flex;align-items:center;justify-content:center}

controller/internal/web/templates/layout.html

@@ -5,6 +5,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>{{.Title}} — Felhom.eu</title>
+    <link rel="icon" type="image/svg+xml" href="/static/felhom-logo.svg">
     <link rel="stylesheet" href="/static/style.css">
     <meta name="csrf-token" content="{{.CSRFToken}}">
     <script>