Add boto3 dependency and update exercise/machine assets

- Added boto3 as a dependency in pyproject.toml and uv.lock.
- Introduced multiple new exercise images in various formats (jpg, webp, avif, png).
- Added new machine images to enhance the workout assets library.

frontend/src/features/workout/hooks.ts

@@ -39,10 +39,11 @@ export function useWorkoutMutations(options: { onStartConflict?: () => void; onF
   });
 
   const addWorkoutItem = useMutation({
-    mutationFn: ({ workoutId, sourceId, kind }: { workoutId: string; sourceId: string; kind: CatalogKind }) =>
+    mutationFn: ({ workoutId, sourceId }: { workoutId: string; sourceId: string; kind: CatalogKind }) =>
       workoutApi.addItem(token, workoutId, {
-        exercise_id: kind === "exercise" ? sourceId : null,
-        equipment_id: kind === "equipment" ? sourceId : null,
+        activity_source_id: sourceId,
+        exercise_id: null,
+        equipment_id: null,
       }),
     onSuccess: refresh,
   });