refactor: clean up verbose and redundant comments

Trim or remove comments that:
- State the obvious (function names already convey purpose)
- Repeat what the code clearly shows
- Are excessively long without adding value

Keep comments that explain *why*, not *what*.

internal/autocomplete/service.go

@@ -27,8 +27,7 @@ import (
 	"time"
 )
 
-// Service fetches search suggestions from an upstream metasearch instance
-// or falls back to Wikipedia's OpenSearch API.
+// Service fetches search suggestions from upstream or Wikipedia OpenSearch.
 type Service struct {
 	upstreamURL string
 	http       *http.Client
@@ -44,7 +43,6 @@ func NewService(upstreamURL string, timeout time.Duration) *Service {
 	}
 }
 
-// Suggestions returns search suggestions for the given query.
 func (s *Service) Suggestions(ctx context.Context, query string) ([]string, error) {
 	if strings.TrimSpace(query) == "" {
 		return nil, nil
@@ -56,7 +54,6 @@ func (s *Service) Suggestions(ctx context.Context, query string) ([]string, erro
 	return s.wikipediaSuggestions(ctx, query)
 }
 
-// upstreamSuggestions proxies to an upstream /autocompleter endpoint.
 func (s *Service) upstreamSuggestions(ctx context.Context, query string) ([]string, error) {
 	u := s.upstreamURL + "/autocompleter?" + url.Values{"q": {query}}.Encode()
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u, nil)