refactor!: simplify task state and PID registry

[MikiEEE]

Summary

• remove the deprecated TaskState container and its stale lifecycle mirror
• make SmallTask fields and scheduler-owned wait registrations the single source of task lifecycle truth
• replace the PID-sorted task list and duplicate used-PID set with one PID-to-task dictionary and bounded allocation cursor
• preserve priority FIFO scheduling, front-resume behavior, deterministic PID-ordered snapshots, and the sleeping-task heap
• reject stale ready and sleeping entries by task identity after PID reuse

Breaking changes

• SmallPackage.TaskState has been removed
• SmallTask.state has been removed
• state_blob parameters have been removed from sleep, wait_signal, and sigSuspendV2

The breaking title intentionally selects a major semantic-version release from the current v1.1.0 baseline.

Validation

• PR refactor(runtime): remove TaskState #32 passed static typing, CPython 3.10-3.13 tests, coverage, and distribution verification
• PR refactor(scheduler): replace sorted PID registry #33 passed static typing, CPython 3.10-3.13 tests, coverage, and distribution verification
• focused scheduler coverage includes priority/FIFO/front ordering, capacity exhaustion, PID reuse, invalid priorities, queued deletion, stale sleeping entries, watcher accounting, and deterministic listing order
• release-policy title validation passed locally

Included work

• refactor(runtime): remove TaskState #32
• refactor(scheduler): replace sorted PID registry #33

Follow-up

• run real-device MicroPython heap and scheduler measurements when supported hardware is available
• audit the separate SmallIO deque constructor for the same MicroPython compatibility concern