Release v0.1.6

Benchmark Truthfulness

• Removed tracemalloc from the timed path of both core and plugin benchmark
  lanes so throughput numbers are no longer distorted by heap sampling
  overhead
• Updated the core and plugin benchmark reports to hide Peak Py Heap when
  heap sampling is intentionally disabled and to explain that throughput is now
  measured without tracemalloc
• Kept the benchmark lane split (core, Kafka, Redis) but made the
  generated reports better match what they actually measure in practice

Runtime Fixes

• Fixed trace_span() to return a zero-allocation singleton scope when
  NoopTracer is active, eliminating per-record span object allocation on the
  hot path for pipelines that do not collect traces
• Fixed MapMiddleware to cache whether its callable is async at construction
  time instead of re-running coroutine-function inspection for every record
• Fixed SinkFanOut.write() to use the same _WRITE_OK singleton fast path
  that write_batch() already used for single-sink pipelines, avoiding
  unnecessary list allocation per record
• Fixed MiddlewareChain.stop_all() to continue stopping remaining middlewares
  when one raises during shutdown, logging each failure instead of aborting the
  shutdown sequence early
• Fixed AIBatchMiddleware.submit() variable shadowing that caused
  UnboundLocalError when the queue was active
• Replaced deprecated asyncio.iscoroutinefunction() usage with
  inspect.iscoroutinefunction() in the middleware and CLI paths that still
  used the old helper

Type Checking

• Added Any imports and type annotations to untyped functions across
  cli/, config/, core/, runner/, middlewares/, sinks/, sources/,
  schema/, metrics/, and ai/ modules
• Fixed on_error parameter defaults in all AI middleware subclasses to use
  OnError.PASSTHROUGH enum value instead of the bare string "passthrough"
• Fixed asyncio.Task, asyncio.Future, and dict generic type arguments
  throughout the codebase
• Removed stale and incorrect type: ignore comments that mypy flagged as
  unused after other fixes landed