feat: implement color theme switcher with dynamic button colors

Complete color theme system (light/dark/auto) with dynamic UI:

Features:
- Color theme switcher with auto/light/dark modes
- Dynamic button colors on hover (purple/yellow/blue per theme)
- localStorage persistence across sessions
- Proper button positioning (desktop and mobile)
- Mobile: 5-button layout with theme before info button

Fixes:
- CSP updated to allow jsDelivr CDN for iconify icons
- Button repositioning: Download PDF and Print Friendly at top
- Hover-only colors (not persistent)
- Mobile button order corrected

Files:
- static/css/color-theme.css - Theme system with CSS variables
- static/js/color-theme.js - Theme switching logic
- templates/partials/color-theme-switcher.html - Button component
- internal/middleware/security.go - CSP fix for jsDelivr
- tests/mjs/13-color-theme-switcher.test.mjs - Comprehensive test
- tests/TEST-SUMMARY.md - Updated test documentation

internal/middleware/security.go

@@ -30,7 +30,7 @@ func SecurityHeaders(next http.Handler) http.Handler {
 
 		// Content Security Policy (comprehensive)
 		csp := "default-src 'self'; " +
-			"script-src 'self' 'unsafe-inline' https://unpkg.com https://code.iconify.design https://matomo.drolo.club; " +
+			"script-src 'self' 'unsafe-inline' https://unpkg.com https://cdn.jsdelivr.net https://matomo.drolo.club; " +
 			"style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; " +
 			"font-src 'self' https://fonts.gstatic.com; " +
 			"img-src 'self' data: https:; " +