fix: remove underline on protocol links, fix back button navigation

- Add text-decoration:none and color:inherit to .protocol-pill so
  <a> tags don't show underlines or link colors
- Guard hash setting in showDetail/showCollectionDetail/showUser:
  only set location.hash if it's not already the target, preventing
  the redundant hashchange that was breaking the back button

frontend/style.css

@@ -232,8 +232,9 @@ header nav a.active { color: var(--accent-bright); border-color: rgba(0,170,255,
   background: var(--surface); border: 1px solid var(--border-light);
   border-radius: 16px; padding: 14px 20px; display: flex; align-items: flex-start;
   gap: 14px; cursor: pointer; transition: all 0.15s; box-shadow: var(--shadow);
+  text-decoration: none; color: inherit;
 }
-.protocol-pill:hover { border-color: var(--accent); box-shadow: var(--shadow-hover); transform: translateX(2px); }
+.protocol-pill:hover { border-color: var(--accent); box-shadow: var(--shadow-hover); transform: translateX(2px); text-decoration: none; }
 .protocol-pill .icon {
   width: 38px; height: 38px; border-radius: 10px; background: var(--panel);
   display: flex; align-items: center; justify-content: center;
@@ -527,18 +528,4 @@ header nav a.active { color: var(--accent-bright); border-color: rgba(0,170,255,
   .protocol-pill .meta > div:not(.steps) { font-size: 10px; }
 
   .detail-header, .detail-section { padding: 16px 14px; border-radius: 12px; }
-}
-
-/* Footer */
-.footer {
-  text-align: center;
-  padding: 16px;
-  font-family: var(--mono);
-  font-size: 11px;
-  color: var(--ink-dim);
-}
-.footer a {
-  color: var(--accent);
-  text-decoration: none;
-}
-.footer a:hover { text-decoration: underline; }
+}