Major changes to fix worker stability:

- Replace pcntl_fork() with pcntl_fork()+pcntl_exec() in MasterProcess
  to avoid Fiber/Revolt segfaults from inherited event loop state
- Add torque:worker hidden artisan command for clean process spawning
- Replace semaphore-gated repeat timer with N pre-spawned Fibers
  (one per concurrency slot) — fixes EventLoop exit when semaphore
  suspended the repeat callback
- Add two-phase job reading: pending recovery (0-0) then new messages (>)
- Aggressive XAUTOCLAIM (min-idle-time=0) to reclaim all stuck messages
- Per-Fiber dedicated Redis connections for XREADGROUP BLOCK
- EventLoop error handler to catch uncaught Fiber exceptions
- Proper signal reset in forked children