feat(ux): collapse Albums sort buttons into a dropdown

Two sort buttons (A–Z Album / A–Z Artist) become one SortDropdown —
same portal popover pattern as the year and genre filters. Button
shows the current choice with an up/down arrow icon. Generic
component, reusable for other pages.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/SortDropdown.tsx

@@ -0,0 +1,133 @@
+import React, { useEffect, useLayoutEffect, useRef, useState } from 'react';
+import { createPortal } from 'react-dom';
+import { ArrowDownUp, Check } from 'lucide-react';
+
+export interface SortOption<V extends string> {
+  value: V;
+  label: string;
+}
+
+interface Props<V extends string> {
+  value: V;
+  options: SortOption<V>[];
+  onChange: (value: V) => void;
+  ariaLabel?: string;
+}
+
+export default function SortDropdown<V extends string>({ value, options, onChange, ariaLabel }: Props<V>) {
+  const [open, setOpen] = useState(false);
+  const [popStyle, setPopStyle] = useState<React.CSSProperties>({});
+
+  const triggerRef = useRef<HTMLButtonElement>(null);
+  const popRef = useRef<HTMLDivElement>(null);
+
+  const current = options.find(o => o.value === value);
+
+  const updatePopStyle = () => {
+    if (!triggerRef.current) return;
+    const rect = triggerRef.current.getBoundingClientRect();
+    const MARGIN = 6;
+    const WIDTH = Math.max(rect.width, 220);
+    const MAX_H = 300;
+    const spaceBelow = window.innerHeight - rect.bottom - MARGIN;
+    const spaceAbove = rect.top - MARGIN;
+    const useAbove = spaceBelow < 160 && spaceAbove > spaceBelow;
+    const left = Math.min(
+      Math.max(rect.left, 8),
+      window.innerWidth - WIDTH - 8,
+    );
+    setPopStyle({
+      position: 'fixed',
+      left,
+      width: WIDTH,
+      ...(useAbove
+        ? { bottom: window.innerHeight - rect.top + MARGIN }
+        : { top: rect.bottom + MARGIN }),
+      maxHeight: Math.min(MAX_H, useAbove ? spaceAbove : spaceBelow),
+      zIndex: 99998,
+    });
+  };
+
+  useLayoutEffect(() => {
+    if (!open) return;
+    updatePopStyle();
+  }, [open]);
+
+  useEffect(() => {
+    if (!open) return;
+    const onResize = () => updatePopStyle();
+    window.addEventListener('resize', onResize);
+    window.addEventListener('scroll', onResize, true);
+    return () => {
+      window.removeEventListener('resize', onResize);
+      window.removeEventListener('scroll', onResize, true);
+    };
+  }, [open]);
+
+  useEffect(() => {
+    if (!open) return;
+    const onDown = (e: MouseEvent) => {
+      if (
+        !triggerRef.current?.contains(e.target as Node) &&
+        !popRef.current?.contains(e.target as Node)
+      ) setOpen(false);
+    };
+    const onKey = (e: KeyboardEvent) => { if (e.key === 'Escape') setOpen(false); };
+    document.addEventListener('mousedown', onDown);
+    document.addEventListener('keydown', onKey);
+    return () => {
+      document.removeEventListener('mousedown', onDown);
+      document.removeEventListener('keydown', onKey);
+    };
+  }, [open]);
+
+  return (
+    <>
+      <button
+        ref={triggerRef}
+        type="button"
+        className="btn btn-surface"
+        onClick={() => setOpen(v => !v)}
+        aria-haspopup="listbox"
+        aria-expanded={open}
+        aria-label={ariaLabel}
+        style={{ display: 'flex', alignItems: 'center', gap: '0.4rem' }}
+      >
+        <ArrowDownUp size={14} />
+        {current?.label ?? value}
+      </button>
+
+      {open && createPortal(
+        <div
+          ref={popRef}
+          className="genre-filter-popover"
+          style={popStyle}
+          role="listbox"
+        >
+          <div className="genre-filter-popover__list">
+            {options.map(opt => {
+              const isSel = opt.value === value;
+              return (
+                <div
+                  key={opt.value}
+                  className={`genre-filter-popover__option${isSel ? ' genre-filter-popover__option--selected' : ''}`}
+                  onClick={() => { onChange(opt.value); setOpen(false); }}
+                  role="option"
+                  aria-selected={isSel}
+                >
+                  <span className="genre-filter-popover__check">
+                    {isSel && <Check size={12} strokeWidth={3} />}
+                  </span>
+                  <span style={{ flex: 1, minWidth: 0, overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }}>
+                    {opt.label}
+                  </span>
+                </div>
+              );
+            })}
+          </div>
+        </div>,
+        document.body,
+      )}
+    </>
+  );
+}

src/pages/Albums.tsx

@@ -2,6 +2,7 @@ import React, { useEffect, useState, useCallback, useRef, useMemo } from 'react'
 import AlbumCard from '../components/AlbumCard';
 import GenreFilterBar from '../components/GenreFilterBar';
 import YearFilterButton from '../components/YearFilterButton';
+import SortDropdown from '../components/SortDropdown';
 import { getAlbumList, getAlbumsByGenre, getAlbum, SubsonicAlbum, buildDownloadUrl } from '../api/subsonic';
 import { useTranslation } from 'react-i18next';
 import { useAuthStore } from '../store/authStore';
@@ -218,16 +219,13 @@ export default function Albums() {
             </>
           ) : (
             <>
-              {!yearActive && sortOptions.map(o => (
+              {!yearActive && (
-                <button
+                <SortDropdown
-                  key={o.value}
+                  value={sort}
-                  className={`btn btn-surface ${sort === o.value ? 'btn-sort-active' : ''}`}
+                  options={sortOptions}
-                  onClick={() => setSort(o.value)}
+                  onChange={setSort}
-                  style={sort === o.value ? { background: 'var(--accent)', color: 'var(--ctp-crust)' } : {}}
+                />
-                >
+              )}
-                  {o.label}
-                </button>
-              ))}
 
               <YearFilterButton
                 from={yearFrom}