analytics viewer: copy-to-clipboard UAs, crawler info links, shared icon-btn

- UA lines click to copy the raw UA; abuse rows with rotating clients
  copy every variation, one per line (uaRaws)
- "Copied!" popup is viewport-fixed at the click point; cell overflow
  clipped the old absolute one
- language tags show their Intl.DisplayNames full name on hover
- a 🔗 link after the pretty UA opens the crawler info page uarite
  provides
- the emoji-symbol dim-until-hover idiom (opacity 0.7 -> 1) is now one
  global .icon-btn class in pagerite.css, shared by the edit pens,
  auth links, editor icon buttons and the new UA link

frontend/src/SiteEditor.vue

@@ -782,14 +782,6 @@ onUnmounted(() => {
   margin-left: auto;
   padding: 0 0.2rem;
   font-size: 1rem;
-  background: none;
-  border: none;
-  cursor: pointer;
-  opacity: 0.7;
-}
-
-.block-head .icon-btn:hover {
-  opacity: 1;
 }
 
 .text-input {