Advance managed execution and durable Active Context

[bhyi4]

Summary

• bind managed writes to prepared target freshness and reviewed execution
• add bounded context, transport, LocalHost, isolated-worker, and recovery contracts
• add durable Active Context sessions with extraction, review, replay, search, and checkpoints
• add preregistered comparison tooling, cross-platform CI definitions, and publication gates

Verification

• seven cumulative commit groups passed in a temporary Git simulation; every real commit tree matched
• committed HEAD isolated distribution contract passed in 121.407 seconds
• 81 source and wheel session contracts passed
• 162-file pre-publication scan and 10 publication-gate tests passed
• four privileged isolation checks remain explicit skips

Boundaries

This PR does not install or activate an operating loader, change production permissions, call a model, deploy, publish a package, or claim general model-quality or token-cost superiority.