支持主机桥接后固定δt与旋转先验，并落盘运动对供可视化直读。

Co-authored-by: Cursor <cursoragent@cursor.com>

imu_lidar/contracts.py

@@ -51,6 +51,12 @@ class CalibrationRequest:
     min_pair_rotation_deg: float = 3.0
     min_pair_translation_m: float = 0.3
     time_offset_search_s: float = 1.0
+    # If set, skip |ω| search and use this constant (host-UTC-bridged sessions: 0).
+    fixed_time_offset_s: float | None = None
+    # Signed 3-axis refine after hand-eye; disable for already-bridged timelines.
+    enable_signed_time_refine: bool = True
+    # Reject signed refine steps that walk farther than this from the coarse δt.
+    max_signed_refine_shift_s: float = 0.05
 
 
 @dataclass