Dogfood PatternKit in ExperimentFramework pipelines and resilience

[JerrettDavis]

Goal

Dogfood PatternKit in ExperimentFramework where the framework already implements common design and integration patterns internally.

Candidate refactors

• Decorator pipeline: evaluate replacing or wrapping ExperimentFramework.Decorators.DecoratorPipeline with PatternKit chain/decorator primitives while preserving public contracts.
• Resilience and fallback policies: map retry/fallback/error policy execution to PatternKit retry, circuit breaker, or chain primitives where behavior aligns.
• Distributed state/locking: review distributed locking abstractions against PatternKit distributed lock/lease primitives.
• Diagnostics event sinks: evaluate PatternKit observer/event notification/audit log for internal event flow.

Acceptance criteria

• Public ExperimentFramework APIs remain source compatible unless explicitly versioned.
• Add focused tests proving behavior parity before/after refactor.
• Document any PatternKit dependency and extension-point guidance.

[JerrettDavis]

Implemented and merged in #101.