fix(studio): stop lane-header clicks from reaching the track row

The prev/next keyframe chevrons and the group toggle diamond let their
click bubble to the ancestor track row, so seeking to a keyframe also
reselected the track. The disclosure caret and the eye already stop it;
these now match.

Truncated labels (layer name, track label, group label, value readout)
also carry a title so the full text is reachable on hover.

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

@@ -50,7 +50,9 @@ export function LayerDisclosureRow({
       >
         ◇
       </span>
-      <span className="min-w-0 flex-1 truncate font-medium">{name}</span>
+      <span className="min-w-0 flex-1 truncate font-medium" title={name}>
+        {name}
+      </span>
     </div>
   );
 }

packages/studio/src/player/components/TimelineTrackHeader.test.tsx

@@ -167,6 +167,37 @@ describe("TimelineTrackHeader", () => {
     act(() => view.root.unmount());
   });
 
+  // The lane header sits inside the track row, whose own click handler selects
+  // the track. Every control in the label column has to own its click, or
+  // seeking to a keyframe also reselects whatever is behind the header.
+  it("keeps lane-header control clicks off the ancestor track row", () => {
+    const onAncestorClick = vi.fn();
+    const view = renderHeader({
+      currentTime: 1,
+      onSeek: vi.fn(),
+      onTogglePropertyGroupKeyframe: vi.fn(),
+    });
+    // React 18 delegates from the root container, so an ancestor of it is where
+    // a leaked click actually shows up.
+    document.body.addEventListener("click", onAncestorClick);
+
+    // Every control in the lane's label column, found by row rather than by
+    // label, so a wording change to one button can't silently drop it here.
+    const controls = view.host.querySelectorAll<HTMLButtonElement>(
+      '[data-property-group="position"] button',
+    );
+    expect(controls.length).toBeGreaterThanOrEqual(3);
+    for (const button of controls) {
+      act(() => {
+        button.dispatchEvent(new MouseEvent("click", { bubbles: true }));
+      });
+    }
+
+    document.body.removeEventListener("click", onAncestorClick);
+    expect(onAncestorClick).not.toHaveBeenCalled();
+    act(() => view.root.unmount());
+  });
+
   it("fills the toggle diamond exactly at that group's keyframe", () => {
     const view = renderHeader({ currentTime: 0.5 });
     const positionToggle = view.host.querySelector<HTMLButtonElement>(

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

@@ -197,7 +197,11 @@ function LegacyTrackHeader({
       {isAudioTrack && (
         <Music size={12} weight="fill" aria-hidden="true" className="text-white/35" />
       )}
-      {showTrackLabel && <span className="min-w-0 flex-1 truncate text-[11px]">{trackLabel}</span>}
+      {showTrackLabel && (
+        <span className="min-w-0 flex-1 truncate text-[11px]" title={trackLabel}>
+          {trackLabel}
+        </span>
+      )}
       <VisibilityButton
         hidden={isTrackHidden}
         trackNumber={trackNumber}
@@ -343,7 +347,10 @@ function PropertyGroupNavigation({
         aria-label={`Previous ${label} keyframe`}
         disabled={!navigation.prevKeyframe}
         className="h-5 w-3 border-0 bg-transparent p-0 text-white/55 hover:text-white disabled:text-white/15"
-        onClick={() => seekTo(navigation.prevKeyframe)}
+        onClick={(event) => {
+          event.stopPropagation();
+          seekTo(navigation.prevKeyframe);
+        }}
       >
         ‹
       </button>
@@ -353,7 +360,10 @@ function PropertyGroupNavigation({
         aria-label={`Next ${label} keyframe`}
         disabled={!navigation.nextKeyframe}
         className="h-5 w-3 border-0 bg-transparent p-0 text-white/55 hover:text-white disabled:text-white/15"
-        onClick={() => seekTo(navigation.nextKeyframe)}
+        onClick={(event) => {
+          event.stopPropagation();
+          seekTo(navigation.nextKeyframe);
+        }}
       >
         ›
       </button>
@@ -427,7 +437,9 @@ function PropertyGroupHeaderRow({
         />
         <span className="absolute left-1.5 top-1/2 h-px w-1.5 bg-white/15" />
       </span>
-      <span className="w-[46px] shrink-0 truncate text-white">{label}</span>
+      <span className="w-[46px] shrink-0 truncate text-white" title={label}>
+        {label}
+      </span>
       <PropertyGroupNavigation
         navigation={navigation}
         label={label}
@@ -439,7 +451,10 @@ function PropertyGroupHeaderRow({
           aria-label={`Toggle ${label} keyframe`}
           title={`${navigation.currentKeyframe ? "Remove" : "Add"} ${label} keyframe`}
           className="flex h-5 w-4 shrink-0 items-center justify-center border-0 bg-transparent p-0 text-[11px] text-[#3CE6AC] focus-visible:outline focus-visible:outline-1 focus-visible:outline-[#3CE6AC]"
-          onClick={() => {
+          onClick={(event) => {
+            // Same as the disclosure caret and the eye: a control in the label
+            // column owns its click, it does not also hit the track row behind it.
+            event.stopPropagation();
             if (expandedElement && toggleTarget) {
               void onTogglePropertyGroupKeyframe?.(expandedElement, toggleTarget);
             }
@@ -448,7 +463,10 @@ function PropertyGroupHeaderRow({
           {navigation.currentKeyframe ? "◆" : "◇"}
         </button>
       </PropertyGroupNavigation>
-      <span className="min-w-0 flex-1 truncate text-right tabular-nums text-white/45">
+      <span
+        className="min-w-0 flex-1 truncate text-right tabular-nums text-white/45"
+        title={valueReadout(lane.group, values)}
+      >
         {valueReadout(lane.group, values)}
       </span>
       <VisibilityButton