Add multi-select download client filter with client type display

public/style.css

@@ -698,6 +698,150 @@ body {
   border-color: var(--accent);
 }
 
+/* Multi-select dropdown container */
+.download-client-filter {
+  position: relative;
+  display: inline-block;
+}
+
+.download-client-dropdown-btn {
+  padding: 4px 8px;
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  background: var(--surface);
+  color: var(--text-primary);
+  font-size: 0.85rem;
+  cursor: pointer;
+  min-width: 140px;
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 8px;
+  transition: background 0.15s, border-color 0.15s;
+}
+
+.download-client-dropdown-btn:hover {
+  background: var(--hover-bg);
+}
+
+.download-client-dropdown-btn:focus {
+  outline: none;
+  border-color: var(--accent);
+}
+
+.download-client-dropdown-btn .dropdown-arrow {
+  font-size: 0.75rem;
+  transition: transform 0.2s;
+}
+
+.download-client-dropdown-btn.open .dropdown-arrow {
+  transform: rotate(180deg);
+}
+
+.download-client-count {
+  background: var(--accent);
+  color: white;
+  padding: 1px 6px;
+  border-radius: 10px;
+  font-size: 0.75rem;
+  font-weight: 500;
+}
+
+/* Dropdown panel */
+.download-client-dropdown {
+  position: absolute;
+  top: 100%;
+  left: 0;
+  margin-top: 4px;
+  background: var(--surface);
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
+  min-width: 200px;
+  max-width: 300px;
+  max-height: 300px;
+  overflow-y: auto;
+  z-index: 1000;
+  display: none;
+}
+
+.download-client-dropdown.open {
+  display: block;
+}
+
+/* Dropdown header with Select All/Deselect All buttons */
+.download-client-dropdown-header {
+  padding: 8px 12px;
+  border-bottom: 1px solid var(--border);
+  display: flex;
+  gap: 8px;
+  position: sticky;
+  top: 0;
+  background: var(--surface);
+  z-index: 1;
+}
+
+.download-client-dropdown-btn-small {
+  padding: 4px 8px;
+  border: 1px solid var(--border);
+  border-radius: 3px;
+  background: var(--surface-alt);
+  color: var(--text-secondary);
+  font-size: 0.75rem;
+  cursor: pointer;
+  transition: background 0.15s, color 0.15s;
+}
+
+.download-client-dropdown-btn-small:hover {
+  background: var(--hover-bg);
+  color: var(--text-primary);
+}
+
+/* Client option row */
+.download-client-option {
+  padding: 8px 12px;
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  cursor: pointer;
+  transition: background 0.15s;
+}
+
+.download-client-option:hover {
+  background: var(--hover-bg);
+}
+
+.download-client-checkbox {
+  width: 16px;
+  height: 16px;
+  margin: 0;
+  cursor: pointer;
+  accent-color: var(--accent);
+}
+
+.download-client-option-label {
+  flex: 1;
+  font-size: 0.85rem;
+  color: var(--text-primary);
+  cursor: pointer;
+}
+
+.download-client-type {
+  font-size: 0.75rem;
+  color: var(--text-secondary);
+  background: var(--surface-alt);
+  padding: 1px 6px;
+  border-radius: 3px;
+}
+
+/* Empty state */
+.download-client-empty {
+  padding: 12px;
+  text-align: center;
+  font-size: 0.85rem;
+  color: var(--text-secondary);
+}
+
 .history-header {
   display: flex;
   align-items: center;