fix(studio): drop dead keyframe menu wiring and close the R1 review items

The diamond context menu still declared `onChangeEase` and `onCopyProperties`
props, and `TimelineOverlays` still threaded `onChangeKeyframeEase` plus a
`keyframeCache` it never read. Nothing on any timeline branch calls them, so
they are removed along with the `onChangeKeyframeEase` callback implementation.

Also from review:
- `deleteSelectedKeyframes` only falls back to the sole keyframed animation when
  there is exactly one. A collapsed selection key carries no animation id, so
  taking the first of several deleted an arbitrary tween's keyframe.
- The duration-less retime test asserts the real 87.601% instead of
  `expect.any(Number)`, so a wrong timing basis fails it.
- `Timeline` wires the keyframe handlers' `onSelectSegment` through to the
  diamonds; it was built and then dropped, so segment ease selection never fired.
- The flat text section arms auto-focus in state rather than reading and
  clearing a ref during render, which Strict Mode's double render swallowed.

packages/studio/src/player/components/KeyframeDiamondContextMenu.tsx

@@ -21,8 +21,6 @@ interface KeyframeDiamondContextMenuProps {
   onClose: () => void;
   onDelete: (elementId: string, target: TimelineKeyframeTarget) => void;
   onDeleteAll: (element: TimelineElement) => void;
-  onChangeEase?: (elementId: string, percentage: number, ease: string) => void;
-  onCopyProperties?: (elementId: string, percentage: number) => void;
   /** Retime the keyframe to the current playhead, preserving its value + ease. */
   onMoveToPlayhead?: (element: TimelineElement, target: TimelineKeyframeTarget) => void;
 }

packages/studio/src/player/components/Timeline.tsx

@@ -75,7 +75,6 @@ export const Timeline = memo(function Timeline({
     onRazorSplitAll,
     onDeleteKeyframe,
     onDeleteAllKeyframes,
-    onChangeKeyframeEase,
     onMoveKeyframeToPlayhead,
     onMoveKeyframe,
   } = useResolvedTimelineEditCallbacks({
@@ -263,7 +262,7 @@ export const Timeline = memo(function Timeline({
   const selectedKeyframes = usePlayerStore((s) => s.selectedKeyframes);
   const toggleSelectedKeyframe = usePlayerStore((s) => s.toggleSelectedKeyframe);
 
-  const { onClickKeyframe, onShiftClickKeyframe, onContextMenuKeyframe } =
+  const { onClickKeyframe, onSelectSegment, onShiftClickKeyframe, onContextMenuKeyframe } =
     useTimelineKeyframeHandlers({
       expandedElements,
       keyframeCache,
@@ -509,6 +508,7 @@ export const Timeline = memo(function Timeline({
           currentTime={currentTime}
           beatAnalysis={adjustedBeatAnalysis}
           onClickKeyframe={onClickKeyframe}
+          onSelectSegment={onSelectSegment}
           onShiftClickKeyframe={onShiftClickKeyframe}
           onMoveKeyframe={onMoveKeyframe}
           onContextMenuKeyframe={onContextMenuKeyframe}
@@ -547,9 +547,7 @@ export const Timeline = memo(function Timeline({
         setKfContextMenu={setKfContextMenu}
         onDeleteKeyframe={onDeleteKeyframe}
         onDeleteAllKeyframes={onDeleteAllKeyframes}
-        onChangeKeyframeEase={onChangeKeyframeEase}
         onMoveKeyframeToPlayhead={onMoveKeyframeToPlayhead}
-        keyframeCache={keyframeCache}
         clipContextMenu={clipContextMenu}
         setClipContextMenu={setClipContextMenu}
         currentTime={currentTime}

packages/studio/src/player/components/TimelineLanes.tsx

@@ -74,6 +74,8 @@ export interface TimelineLaneBaseProps {
   currentTime: number;
   onClickKeyframe?: (element: TimelineElement, keyframe: TimelineKeyframeTarget) => void;
   onShiftClickKeyframe?: (elementId: string, keyframe: TimelineKeyframeTarget) => void;
+  /** Click on the segment BETWEEN two diamonds: selects it to edit its ease. */
+  onSelectSegment?: (elementId: string, keyframe: TimelineKeyframeTarget) => void;
   onContextMenuKeyframe?: (
     e: React.MouseEvent,
     elementId: string,
@@ -141,6 +143,7 @@ export function TimelineLanes({
   currentTime,
   onClickKeyframe,
   onShiftClickKeyframe,
+  onSelectSegment,
   onContextMenuKeyframe,
   onMoveKeyframe,
   onContextMenuClip,
@@ -482,6 +485,7 @@ export function TimelineLanes({
                               onClickKeyframe?.(previewElement, keyframe)
                             }
                             onShiftClickKeyframe={onShiftClickKeyframe}
+                            onSelectSegment={onSelectSegment}
                             onContextMenuKeyframe={onContextMenuKeyframe}
                             onMoveKeyframe={onMoveKeyframe}
                             suppressClickRef={suppressClickRef}

packages/studio/src/player/components/TimelineOverlays.tsx

@@ -1,4 +1,4 @@
-import type { KeyframeCacheEntry, TimelineElement } from "../store/playerStore";
+import type { TimelineElement } from "../store/playerStore";
 import type { TimelineTheme } from "./timelineTheme";
 import type { TimelineRangeSelection } from "./timelineEditing";
 import type { TimelineEditCallbacks } from "./timelineCallbacks";
@@ -38,9 +38,7 @@ interface TimelineOverlaysProps {
   setKfContextMenu: (value: KeyframeDiamondContextMenuState | null) => void;
   onDeleteKeyframe: TimelineEditCallbacks["onDeleteKeyframe"];
   onDeleteAllKeyframes: TimelineEditCallbacks["onDeleteAllKeyframes"];
-  onChangeKeyframeEase: TimelineEditCallbacks["onChangeKeyframeEase"];
   onMoveKeyframeToPlayhead: TimelineEditCallbacks["onMoveKeyframeToPlayhead"];
-  keyframeCache: Map<string, KeyframeCacheEntry>;
   clipContextMenu: ClipContextMenuState | null;
   setClipContextMenu: (value: ClipContextMenuState | null) => void;
   currentTime: number;
@@ -68,9 +66,7 @@ export function TimelineOverlays({
   setKfContextMenu,
   onDeleteKeyframe,
   onDeleteAllKeyframes,
-  onChangeKeyframeEase,
   onMoveKeyframeToPlayhead,
-  keyframeCache,
   clipContextMenu,
   setClipContextMenu,
   currentTime,
@@ -108,19 +104,11 @@ export function TimelineOverlays({
           onClose={() => setKfContextMenu(null)}
           onDelete={(elId, target) => onDeleteKeyframe?.(elId, target)}
           onDeleteAll={(elId) => onDeleteAllKeyframes?.(elId)}
-          onChangeEase={(elId, pct, ease) => onChangeKeyframeEase?.(elId, pct, ease)}
           onMoveToPlayhead={
             onMoveKeyframeToPlayhead
               ? (element, target) => onMoveKeyframeToPlayhead(element, target)
               : undefined
           }
-          onCopyProperties={(elId, pct) => {
-            const kfData = keyframeCache.get(elId);
-            const kf = kfData?.keyframes.find((k) => k.percentage === pct);
-            if (kf) {
-              void navigator.clipboard.writeText(JSON.stringify(kf.properties, null, 2));
-            }
-          }}
         />
       )}
 

packages/studio/src/player/components/timelineCallbacks.ts

@@ -74,7 +74,6 @@ export interface TimelineEditCallbacks {
   onRazorSplitAll?: (splitTime: number) => Promise<void> | void;
   onDeleteKeyframe?: (elementId: string, keyframe: TimelineKeyframeTarget) => void;
   onDeleteAllKeyframes?: (element: TimelineElement) => void;
-  onChangeKeyframeEase?: (elementId: string, percentage: number, ease: string) => void;
   onMoveKeyframeToPlayhead?: (element: TimelineElement, keyframe: TimelineKeyframeTarget) => void;
   /** Drag-to-retime: `keyframe` identifies the dragged keyframe (its percentage
    *  is clip-relative), `toClipPercentage` is the neighbour-clamped drop. */