Add configurable taskFlow memory policies and session reset handling for verifier/developer

[hlibr]

Motivation

• Introduce configurable memory policies to control whether developer and verifier agent sessions are preserved across retries and different failure modes.
• Ensure verifier malformed outputs and runtime errors can be classified separately from normal verification failures so memory reset policies can be applied precisely.

Description

• Add a taskFlow.memory schema with options keepDeveloperMemory, keepVerifierMemoryOnDeveloperFailure, and verifierSelfFailureMemory (values: keep, reset, reset_on_malformed_output) in config.ts and load default values when missing.
• Extend the task flow engine (runTaskFlow) to detect whether a verifier transition was due to an unmatched/malformed output versus a verification failure, and pass a reason (verification_failed | malformed_output | error) into applyVerifyFailure.
• Implement resetStageMemory in index.ts to dispose existing runners, increment per-stage sessionResetCounts, and create new session files, and call it from applyVerifyFailure according to the configured memory policy.
• Add sessionResetCounts to TaskState in state.ts so resets are tracked per task stage.
• Update the default workflow file /.pi/workflows/default.workflow.json and README.md to include new taskFlow.memory defaults and documentation.
• Add and update unit tests in tests/config.test.ts, tests/config-extended.test.ts, and tests/engine.test.ts to cover schema validation, defaults, custom memory policies, verifier retry behavior, and reason propagation.

Testing

• Ran the unit test suite for the workflow orchestrator (tests/config.test.ts, tests/config-extended.test.ts, tests/engine.test.ts) which exercise schema loading, memory defaults/validation, and runTaskFlow behaviors, and all tests passed.

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Codex Task