docs: fix broken links, update versions and test counts

5-expert orchestrated cleanup audit findings:
- Fix broken security doc links (docs/SECURITY.md → doc/9-SECURITY.md)
- Update Go version requirement (1.21+ → 1.25.1+)
- Correct test count (39 → 44 test files)
- Fix ZOOM_IMPLEMENTATION.md filename reference
- Update last modified dates to 2025-12-02

doc/README.md

@@ -50,7 +50,7 @@
 | 2 | [MODERN-WEB-TECHNIQUES.md](2-MODERN-WEB-TECHNIQUES.md) | HTMX/Hyperscript frontend architecture, component patterns, ADRs | Frontend developers |
 | 3 | [API.md](3-API.md) | Complete API reference with all endpoints | API consumers, integrators |
 | 4 | [HYPERSCRIPT-RULES.md](4-HYPERSCRIPT-RULES.md) | Hyperscript coding conventions | Frontend developers |
-| 5 | [ZOOM_IMPLEMENTATION.md](5-ZOOM-IMPLEMENTATION.md) | Zoom feature implementation details | Feature developers |
+| 5 | [ZOOM-IMPLEMENTATION.md](5-ZOOM-IMPLEMENTATION.md) | Zoom feature implementation details | Feature developers |
 | 12 | [CSS-ARCHITECTURE.md](12-CSS-ARCHITECTURE.md) | Modular CSS structure, ITCSS layers, HTMX integration | Frontend developers, designers |
 | 13 | [TOAST-NOTIFICATIONS.md](13-TOAST-NOTIFICATIONS.md) | Toast notification system, PDF download feedback, user notifications | Frontend developers, UX designers |
 | 14 | [BACKEND-HANDLERS.md](14-BACKEND-HANDLERS.md) | Handler architecture, type safety, middleware pattern, testing strategy | Backend developers |
@@ -152,6 +152,6 @@ All documentation in this project follows these standards:
 
 ---
 
-**Last Updated**: 2025-12-01
+**Last Updated**: 2025-12-02
 **Documentation Status**: ✅ Clean, organized, single doc/ folder
 **Total Active Docs**: 19 core documents + archive