style(design): migrate to DESIGN.md system

Full visual migration: Space Grotesk + DM Sans + JetBrains Mono fonts,
warm amber two-accent system (amber=state, blue=action), dark mode with
CSS vars + localStorage + FOUC prevention, mobile bottom nav (5 tabs),
full-width tables, error/skipped dot glow, ~13 hardcoded hex replaced
with CSS vars in 4 JS files, 5 new E2E tests.

Files: style.css (full rewrite), base.html (fonts, theme script, dark
toggle, bottom nav), settings.html (dark toggle card), dashboard.js,
logs.js, mappings.js, settings.js (color vars), 5 templates (bnav
active blocks), test_design_system_e2e.py (NEW).

Cache-bust: style.css?v=18, shared.js?v=14, dashboard.js?v=27,
logs.js?v=13, mappings.js?v=12, settings.js?v=8

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/templates/missing_skus.html

@@ -1,6 +1,7 @@
 {% extends "base.html" %}
 {% block title %}SKU-uri Lipsa - GoMag Import{% endblock %}
 {% block nav_missing %}active{% endblock %}
+{% block bnav_missing %}active{% endblock %}
 
 {% block content %}
 <div class="d-flex justify-content-between align-items-center mb-4">