fix(lab): stabilize replay and densify LiDAR overlay

src/k1link/web/m48s_fixed_class_detector_lab_api.py

@@ -159,11 +159,40 @@ def build_m48s_fixed_class_detector_lab_router(
         result_id: str,
         start: int = Query(default=0, ge=0),
         count: int = Query(default=12, ge=1, le=RECORDED_SPATIAL_MAX_CHUNK_FRAMES),
-    ) -> dict[str, object]:
+    ) -> Response:
         try:
-            return timeline(result_id).chunk(start_sequence=start, frame_count=count)
+            content = timeline(result_id).chunk_json(
+                start_sequence=start,
+                frame_count=count,
+            )
         except M48sReplayTimelineError:
             raise HTTPException(status_code=404, detail="M4.8S timeline chunk not found") from None
+        return Response(
+            content=content,
+            media_type="application/json",
+            headers={
+                "Cache-Control": "private, max-age=31536000, immutable",
+                "X-Content-Type-Options": "nosniff",
+            },
+        )
+
+    @router.get("/{result_id}/timeline/frames/{sequence}/camera-points")
+    def get_timeline_camera_points(result_id: str, sequence: int) -> Response:
+        try:
+            content = timeline(result_id).camera_point_overlay_json(sequence=sequence)
+        except M48sReplayTimelineError:
+            raise HTTPException(
+                status_code=404,
+                detail="M4.8S camera point overlay not found",
+            ) from None
+        return Response(
+            content=content,
+            media_type="application/json",
+            headers={
+                "Cache-Control": "private, max-age=31536000, immutable",
+                "X-Content-Type-Options": "nosniff",
+            },
+        )
 
     @router.get("/{result_id}/timeline/frames/{sequence}/camera")
     def get_timeline_camera(result_id: str, sequence: int) -> Response: