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/style.css

@@ -64,6 +64,8 @@
   --footer-text: rgba(255, 255, 255, 0.9);
   --input-bg: #ffffff;
   --select-bg: #ffffff;
+  --unmatched-tag-bg: #fff3e0;
+  --unmatched-tag-color: #e65100;
 }
 
 [data-theme="dark"] {
@@ -100,6 +102,8 @@
   --footer-text: rgba(200, 200, 220, 0.8);
   --input-bg: #2a2a3d;
   --select-bg: #2a2a3d;
+  --unmatched-tag-bg: #3d2a00;
+  --unmatched-tag-color: #ffb74d;
 }
 
 [data-theme="mono"] {
@@ -136,6 +140,8 @@
   --footer-text: rgba(180, 180, 180, 0.7);
   --input-bg: #252525;
   --select-bg: #252525;
+  --unmatched-tag-bg: #2a2a2a;
+  --unmatched-tag-color: #a0a0a0;
 }
 
 /* ===== Base ===== */
@@ -734,6 +740,12 @@ body {
   white-space: nowrap;
 }
 
+.download-user-badge.unmatched {
+  background: var(--unmatched-tag-bg);
+  color: var(--unmatched-tag-color);
+  margin-left: 0;
+}
+
 /* ===== Status Button ===== */
 .status-btn {
   padding: 4px 12px;