feat: feature the agentic-environment guide on the landing page; add a site favicon

bitwarden-switch/password-manager-overview.html

@@ -3,6 +3,7 @@
 <head>
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
+<link rel="icon" href="/favicon.svg" type="image/svg+xml">
 <title data-i18n="page_title">Your Passwords Are the Keys to Your Whole Life</title>
 <style>
 /* =========================================================================