style: remove hyphens from compound adjectives in comments and messages

Remove hyphens from compound adjectives such as "logged-in", "one-time", "password-protected", "full-height", "multi-file", and "S3-compatible" in comments, test error messages, and UI labels to improve readability and consistency.

backend/libs/handlers/meta.go

@@ -15,7 +15,7 @@ func (a *App) RobotsTxt(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprintf(w, `User-agent: *
 Allow: /
 
-# Private routes — do not crawl
+# Private routes. do not crawl
 Disallow: /admin/
 Disallow: /api/
 Disallow: /app/