docs: add comprehensive documentation for today's work

Technical Documentation:
- docs/development/architecture-fixes-2026-01.md: Complete guide to
  all architecture validation fixes (62 -> 0 errors)

User Guides:
- docs/guides/email-templates.md: How-to guide for vendors and admins
  to use the email template customization system

Implementation Docs:
- docs/implementation/password-reset-implementation.md: Technical
  documentation for the password reset feature
- Updated email-templates-architecture.md with EmailTemplateService
  documentation and related links

Bugfix:
- Fixed TemplateListItem Pydantic model to match service output
  (languages vs available_languages field name)

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

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

mkdocs.yml

@@ -135,6 +135,7 @@ nav:
         - Init Guide: development/database-seeder/database-init-guide.md
         - Quick Reference: development/database-seeder/database-quick-reference-guide.md
       - Seed Scripts Audit: development/seed-scripts-audit.md
+      - Architecture Fixes (Jan 2026): development/architecture-fixes-2026-01.md
       - PyCharm Setup:
         - Make Configuration: development/pycharm-configuration-make.md
         - Troubleshooting: development/troubleshooting.md
@@ -169,6 +170,7 @@ nav:
       - Vendor Frontend Parity: implementation/vendor-frontend-parity-plan.md
       - Stock Management Integration: implementation/stock-management-integration.md
       - Email Templates Architecture: implementation/email-templates-architecture.md
+      - Password Reset: implementation/password-reset-implementation.md
 
     # --- Testing ---
     - Testing:
@@ -216,6 +218,7 @@ nav:
       - Product Management: guides/product-management.md
       - Inventory Management: guides/inventory-management.md
       - Subscription Tier Management: guides/subscription-tier-management.md
+      - Email Templates: guides/email-templates.md
       - Shop Setup: guides/shop-setup.md
       - CSV Import: guides/csv-import.md
       - Marketplace Integration: guides/marketplace-integration.md