feat(fusion_clock): native recurring shifts engine [A4-A5]

fusion.clock.schedule.recurrence (repeat every N day/week/month/year;
forever/until/N-times) re-fit from planning.recurrency onto per-day rows;
daily generation cron; _fclk_on_leave skip; planner Repeat…/Stop-repeat
UI + endpoints; recurrence + role indicators on cells.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

fusion_clock/models/__init__.py

@@ -12,6 +12,7 @@ from . import clock_activity_log
 from . import clock_leave_request
 from . import clock_role
 from . import clock_shift
+from . import clock_recurrence
 from . import clock_schedule
 from . import clock_correction
 from . import res_company