feat(audiobooks): show current chapter in MiniBar left column

Renders playback.currentChapter.title between the book title and the
time row. Truncates with a tooltip; absent when the chapter list is
empty or the current position falls outside any chapter.

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

web/src/pages/audiobooks/player/MiniBar.test.tsx

@@ -43,4 +43,27 @@ describe("MiniBar", () => {
     await userEvent.click(screen.getByRole("button", { name: /close player/i }));
     expect(onClose).toHaveBeenCalled();
   });
+
+  it("renders the current chapter title under the book title", () => {
+    render(
+      <MiniBar
+        title="X"
+        playback={makePlayback({
+          currentChapter: {
+            index: 6,
+            title: "The Astrophage",
+            start_seconds: 0,
+            end_seconds: 100,
+            source: "embedded",
+          },
+        })}
+      />,
+    );
+    expect(screen.getByText("The Astrophage")).toBeInTheDocument();
+  });
+
+  it("omits the chapter row when no current chapter is known", () => {
+    render(<MiniBar title="X" playback={makePlayback({ currentChapter: null })} />);
+    expect(screen.queryByTestId("minibar-chapter-title")).not.toBeInTheDocument();
+  });
 });

web/src/pages/audiobooks/player/MiniBar.tsx

@@ -38,6 +38,15 @@ export function MiniBar({ title, playback, onClose }: MiniBarProps) {
               {title}
             </div>
           ) : null}
+          {playback.currentChapter ? (
+            <div
+              data-testid="minibar-chapter-title"
+              className="text-muted-foreground truncate text-[11px] leading-tight"
+              title={playback.currentChapter.title}
+            >
+              {playback.currentChapter.title}
+            </div>
+          ) : null}
           <div className="text-muted-foreground flex items-center gap-2 text-[10px] leading-tight uppercase">
             <span className="font-mono text-[11px] tracking-[0.12em] normal-case tabular-nums">
               {formatTime(playback.currentTime)}