Rename unused parameters to _ to satisfy linter

internal/handlers/image.go

@@ -7,7 +7,7 @@ import (
 // HandleImage handles the main image proxy route:
 // /v1/image/<host>/<path>/<width>x<height>.<format>
 func (s *Handlers) HandleImage() http.HandlerFunc {
-	return func(w http.ResponseWriter, req *http.Request) {
+	return func(_ http.ResponseWriter, _ *http.Request) {
 		// FIXME: Implement image proxy handler
 		// - Parse URL to extract host, path, size, format
 		// - Validate signature and expiration
@@ -19,9 +19,9 @@ func (s *Handlers) HandleImage() http.HandlerFunc {
 	}
 }
 
-// HandleRobotsTxt serves robots.txt to prevent search engine crawling
+// HandleRobotsTxt serves robots.txt to prevent search engine crawling.
 func (s *Handlers) HandleRobotsTxt() http.HandlerFunc {
-	return func(w http.ResponseWriter, req *http.Request) {
+	return func(_ http.ResponseWriter, _ *http.Request) {
 		// FIXME: Implement robots.txt handler
 		panic("unimplemented")
 	}