feat(web): sync-conflict banner at top of media item page + end-time help row

- A progress sync conflict used to be flagged only inside the progress
  card, far down a long page. An unresolved conflict now also renders
  a full-width warning strip at the very top (under the app bar) that
  opens the same resolution modal on click. Rendered from the same
  ActiveConflict the progress section uses — absent when clean.
- Shortcuts dialog Mouse section gains an 'End time' row: click to
  cycle total → book left → chapter left (§10's toggle was
  undiscoverable).

templates/book_detail.templ

@@ -52,6 +52,23 @@ templ BookDetail(user User, book handlers.MediaDetail, errorMessage string, tomb
 			data-conflict-winner={ conflictWinnerSource(book.ActiveConflict) }
 		>
 			@Header(user, "/media/{ uuidToString(book.ID) }")
+			if book.ActiveConflict != nil {
+				<!-- Sync-conflict banner (user request): the progress
+				     card's warning sits far down a long page — this
+				     strip is unmissable at the very top, and clicking
+				     it opens the same resolution modal. -->
+				<button
+					type="button"
+					@click="showProgressSyncModal()"
+					class="w-full flex items-center gap-3 px-4 sm:px-6 lg:px-8 py-3 text-left"
+					style="background-color: color-mix(in srgb, var(--status-warning) 14%, transparent); border-bottom: 1px solid var(--status-warning);"
+				>
+					@Icon("alert", "h-5 w-5 shrink-0")
+					<span class="text-sm" style="color: var(--text-primary);">
+						Progress sync conflict detected on this item — click to review and resolve.
+					</span>
+				</button>
+			}
 			<!-- Hero with blurred cover backdrop -->
 			<div class="relative overflow-hidden">
 				if book.CoverImagePath.Valid && book.CoverImagePath.String != "" {

web/src/audio-keys.ts

@@ -232,6 +232,10 @@ export const MOUSE_GUIDE: readonly PointerGuideRow[] = [
   { label: "Shift + click", description: "Jump to the nearest chapter line" },
   { label: "Shift + drag", description: "Precision rail (±5 min) around the nearest line" },
   { label: "Wheel", description: "Nudge ±5s (Shift: ±60s)" },
+  {
+    label: "End time",
+    description: "Click to cycle the −label: total → book left → chapter left",
+  },
 ];
 
 export const TOUCH_GUIDE: readonly PointerGuideRow[] = [