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/static/css/40-docs.css

@@ -11,7 +11,7 @@
 }
 
 /* ============================================================
-   API documentation — sidebar layout
+   API documentation: sidebar layout
    ============================================================ */
 
 .api-docs {
@@ -315,6 +315,7 @@
 .method-get { background: #2563eb; }
 .method-post { background: #16a34a; }
 .method-put { background: #d97706; }
+.method-delete { background: #dc2626; }
 
 .endpoint-list {
   display: flex;