Add per-joint limits, joint-space interpolation, grip/release, --up/--down

- Add per-joint angle limits (J2=-110..115, J3=-120..145, J4=-90..130)
  with CLI overrides and validation
- Replace Cartesian interpolation with joint-space interpolation in
  pose mode to guarantee intermediate steps stay within joint limits
- Add --up/--down mutually exclusive groups to both joints and pose
  modes; pose mode auto-detects from z when neither is specified
- Add --grip/--release for J6 control (GRIP/RELEASE_ANGLE placeholders)
- Update cached state to match latest run

tools/.udp_control_state.json

@@ -1,8 +1,8 @@
 {
-  "height": 0,
-  "j2": -90,
-  "j3": 140,
-  "j4": 25,
-  "j5": 81,
+  "height": -280,
+  "j2": -6,
+  "j3": 122,
+  "j4": -80,
+  "j5": -100,
   "j6": 0
 }