V2 Slice 18: Provider Session resumes after crash or context exhaustion

[notadamking]

Source PRD: #64

What to build

Recover provider Worker execution after crash, interruption, or context exhaustion by resuming under the same Assignment using generated Task Progress Summary and Checkpoint context, then continuing through PR review and merge.

Acceptance criteria

• A provider Worker Session can be marked recoverably interrupted or context-exhausted after writing a Checkpoint.
• Scheduler keeps the Assignment recoverable and creates or continues a Session according to adapter capability.
• The resumed provider Worker receives a generated Task Progress Summary with Checkpoint citations.
• The resumed workflow completes code change, PR review, policy, and merge.
• Operator-facing Session and Task views distinguish interruption, resume, and final completion.

Blocked by

• V2 Slice 05: Provider Worker checkpoints during Task execution #69
• V2 Slice 12: Autopilot Agent Review merges without Human Review #76