scheduler: shift=5.159 to match the deployed denoise schedule

The serving stack constructs FlowMatchDiscreteScheduler(shift=5.159)
(deploy/xvideo/config.py), giving 2-step sigmas [1.0, 0.8376, 0.0].
With shift=1.0 the pipeline denoised along [1.0, 0.5, 0.0] — a schedule
the distilled checkpoint was never trained on.

Verified: with shift=5.159 the JoyVideoEditPipeline sigma/timestep
trajectory (raw linspace sigmas -> config-shift in set_timesteps)
matches the deployment scheduler exactly.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scheduler/scheduler_config.json

@@ -7,7 +7,7 @@
   "max_image_seq_len": 4096,
   "max_shift": 1.15,
   "num_train_timesteps": 1000,
-  "shift": 1.0,
+  "shift": 5.159,
   "shift_terminal": null,
   "stochastic_sampling": false,
   "time_shift_type": "exponential",