style: fix password template bg to match landing page (#e8edf4)

Replace StatiCrypt template color variables with hardcoded values
matching the Sistema A design system for visual consistency.

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

Author: jmacot

password_template.html

@@ -15,10 +15,10 @@
   <link href="https://fonts.googleapis.com/css2?family=DM+Serif+Display:ital@0;1&family=DM+Mono:wght@400;500&family=DM+Sans:wght@300;400;500&display=swap" rel="stylesheet">
   <style>
     :root {
-      --bg: /*[|template_color_secondary|]*/0;
+      --bg: #e8edf4;
       --surface: #ffffff;
       --border: #e2e8f0;
-      --accent: /*[|template_color_primary|]*/0;
+      --accent: #1a3a5c;
       --accent-hover: #14304f;
       --ink: #0f172a;
       --ink-muted: #64748b;