feat: multi-tag badges for showAll — amber for unmatched, accent for matched

- server: add extractAllTags() returning all tag labels for a series/movie
- server: showAll now includes items with ANY tag (not just user-matched);
  non-admin path unchanged (must match current user's tag)
- server: replace userTag with allTags[] + matchedUserTag on every download object
- frontend: render all tags in header; unmatched tags amber (left), matched
  user tag in accent colour (rightmost); only visible in showAll mode
- css: add --unmatched-tag-bg/color variables to all three themes (light,
  dark, mono) and .download-user-badge.unmatched style

public/app.js

@@ -434,11 +434,20 @@ function createDownloadCard(download) {
     infoDiv.appendChild(movie);
   }
 
-  if (showAll && download.userTag) {
-    const userBadge = document.createElement('span');
-    userBadge.className = 'download-user-badge';
-    userBadge.textContent = download.userTag;
-    header.appendChild(userBadge);
+  if (showAll && download.allTags && download.allTags.length > 0) {
+    const unmatchedTags = download.allTags.filter(t => t !== download.matchedUserTag);
+    for (const tag of unmatchedTags) {
+      const badge = document.createElement('span');
+      badge.className = 'download-user-badge unmatched';
+      badge.textContent = tag;
+      header.appendChild(badge);
+    }
+    if (download.matchedUserTag) {
+      const matchedBadge = document.createElement('span');
+      matchedBadge.className = 'download-user-badge';
+      matchedBadge.textContent = download.matchedUserTag;
+      header.appendChild(matchedBadge);
+    }
   }
   
   const details = document.createElement('div');