OrchestrateLang v0.8.1

The glue around a synchronous tick is a few nanoseconds, down from about forty.

Changed

• Library mode: the glue around a synchronous tick is a few nanoseconds. tick_sync no
  longer enters the runtime, scopes a task-local, or takes an async mutex per frame: the
  program's state sits in a slot entered with two flag stores and two loads, every hook
  body binds its instance once so a host call is the trait call and one branch, the clock
  advances with an integer add, and an idle tick never builds the event drain. On an Apple
  M2 an empty tick went from 45 ns to 8 ns per tick_sync, and each host call in a hook
  from about 3 ns to about 1.5 ns, no more than the trait call itself. Nothing observable changed: tick,
  fixed_tick, the block_on fallback for a body that waits, deterministic mode,
  stop_orch(), shutdown, event ordering, and the "a tick is already running" error on a
  re-entered tick are as before. The ignored test glue_cost in tests/library_tests.rs
  measures the three cases.
• Library mode: sleep, landline budgets, and workers started inside a hook no longer need
  the calling thread to be inside the runtime's context; the library carries the handle it
  was started with, so tick_sync works from any thread that holds the runtime.
• Library mode: a failed host call is reported as
  [orchestrate] host call <group>.<name> failed: <error> — the call's name is now part of
  the message — still at error level through Host::log, still yielding the return type's
  default, through one shared cold function rather than a closure at every call site.