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

go.mod

@@ -5,7 +5,9 @@ go 1.25.1
 require (
 	github.com/chromedp/cdproto v0.0.0-20250724212937-08a3db8b4327
 	github.com/chromedp/chromedp v0.14.2
+	github.com/go-git/go-git/v5 v5.16.4
 	github.com/joho/godotenv v1.5.1
+	github.com/k3a/html2text v1.2.1
 )
 
 require (
@@ -18,7 +20,6 @@ require (
 	github.com/emirpasic/gods v1.18.1 // indirect
 	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
 	github.com/go-git/go-billy/v5 v5.6.2 // indirect
-	github.com/go-git/go-git/v5 v5.16.4 // indirect
 	github.com/go-json-experiment/json v0.0.0-20250725192818-e39067aee2d2 // indirect
 	github.com/gobwas/httphead v0.1.0 // indirect
 	github.com/gobwas/pool v0.2.1 // indirect