fix: replace inline SVGs with $icon() helper (FE-002)

Convert 90 inline SVG icons to use the shared $icon() helper function
across shop and vendor templates for consistency and maintainability.

Templates updated:
- Shop: checkout, products, login, register, forgot/reset-password
- Shop account: addresses, dashboard, messages, order-detail, orders, profile
- Vendor: billing, login, onboarding, team, landing pages (4 variants)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/templates/vendor/landing-minimal.html

@@ -1,4 +1,5 @@
 {# app/templates/vendor/landing-minimal.html #}
+{# standalone #}
 {# Minimal Landing Page Template - Ultra Clean #}
 {% extends "shop/base.html" %}
 
@@ -40,9 +41,7 @@
                class="inline-flex items-center justify-center px-10 py-5 text-xl font-semibold rounded-full text-white bg-primary hover:bg-primary-dark transition-all transform hover:scale-105 shadow-2xl"
                style="background-color: var(--color-primary)">
                 Enter Shop
-                <svg class="w-6 h-6 ml-3" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-                    <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M13 7l5 5m0 0l-5 5m5-5H6"></path>
-                </svg>
+                <span class="w-6 h-6 ml-3" x-html="$icon('arrow-right', 'w-6 h-6')"></span>
             </a>
         </div>