Phase 1c: prune remaining dead functions, unused imports, quarantine Genesis

- uc480_camera: drop never-called _capture_paused/get_framerate (the
  hardware question _capture_paused encoded is now in KNOWN_ISSUES.md)
- t3r_protocol: drop read_reg/write_reg/decode_reg/Reg (commands never
  wired into the driver)
- bbd20x: drop _update0x0212 (never dispatched) and 8 of 9 unused
  trigger convenience wrappers; apt_constants: drop TriggerBitsStepper
  (servo-only rig)
- ruff --fix: 35 unused imports across all apps; drop unused T3R_BAUD
- genesis_core.py: quarantine warning header; docs/genesis_verification.md
  bench checklist for the 7 divergences vs tools/genesis_laser_gui.py

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

hardware/pybbd202/apt_constants.py

@@ -32,16 +32,6 @@ class StatusBits(IntFlag):
                     MOT_SB_COMMUTATIONERROR | MOT_SB_OVERLOAD |
                     MOT_SB_ERROR | MOT_SB_INSTRERROR)
 
-class TriggerBitsStepper(IntFlag):
-    TRIGIN_ENABLE = 0x01,
-    TRIGOUT_ENABLE = 0x02,
-    TRIGOUT_MODEFOLLOW = 0x04,
-    TRIGOUT_MODEMOVEEND = 0x08,
-    TRIG_RELMOVE = 0x10,
-    TRIG_ABSMOVE = 0x20,
-    TRIG_HOMEMOVE = 0x40,
-    TRIGOUT_NOTRIGIN = 0x80
-
 class TriggerBitsServo(IntFlag):
     TRIGIN_HIGH = 0x01
     TRIGIN_RELMOVE = 0x02