feat: Add plain text CV endpoint and contact form with security

Plain text endpoint:
- Add /text route for plain text CV (for curl/AI crawlers)
- Use k3a/html2text library for HTML-to-text conversion
- Add Plain Text button to hamburger menu with UI translations

Contact form feature:
- Add ContactHandler with proper email service integration
- Add CSRF protection middleware
- Add rate limiting (5 submissions/hour per IP)
- Add honeypot and timing-based bot protection
- Add input validation with detailed error messages
- Add security logging middleware
- Add browser-only middleware for API protection

Code quality:
- Fix all golangci-lint errcheck warnings for w.Write calls
- Remove duplicate getClientIP functions
- Wire up ContactHandler in routes.Setup

internal/routes/routes.go

@@ -9,7 +9,7 @@ import (
 )
 
 // Setup configures all application routes and middleware
-func Setup(cvHandler *handlers.CVHandler, healthHandler *handlers.HealthHandler) http.Handler {
+func Setup(cvHandler *handlers.CVHandler, healthHandler *handlers.HealthHandler, contactHandler *handlers.ContactHandler) http.Handler {
 	mux := http.NewServeMux()
 
 	// Shortcut routes for default CV (year-aware) - MUST be before "/" route
@@ -19,6 +19,7 @@ func Setup(cvHandler *handlers.CVHandler, healthHandler *handlers.HealthHandler)
 	// Public routes
 	mux.HandleFunc("/", cvHandler.Home)
 	mux.HandleFunc("/cv", cvHandler.CVContent)
+	mux.HandleFunc("/text", cvHandler.PlainText) // Plain text version for curl/AI
 	mux.HandleFunc("/health", healthHandler.Check)
 
 	// HTMX endpoints for interactive controls
@@ -27,6 +28,13 @@ func Setup(cvHandler *handlers.CVHandler, healthHandler *handlers.HealthHandler)
 	mux.HandleFunc("/toggle/icons", cvHandler.ToggleIcons)
 	mux.HandleFunc("/toggle/theme", cvHandler.ToggleTheme)
 
+	// Contact form endpoint (simple rate limiting)
+	contactRateLimiter := middleware.NewRateLimiter(5, 1*time.Hour)
+	protectedContactHandler := contactRateLimiter.Middleware(
+		http.HandlerFunc(contactHandler.Submit),
+	)
+	mux.Handle("/api/contact", protectedContactHandler)
+
 	// Protected PDF endpoint with rate limiting (3 requests/minute per IP)
 	pdfRateLimiter := middleware.NewRateLimiter(3, 1*time.Minute)
 	protectedPDFHandler := middleware.OriginChecker(