Add plan export as JSON contract

[blindzero]

This PR introduces a canonical, deterministic JSON export for IdLE lifecycle plans.
The exported artifact is a stable contract intended for approvals, auditing, CI checks, and host integrations.

Scope

• Implements a plan export that is explicitly not an internal object dump
• Freezes the exported shape via a formal specification
• Adds contract tests to prevent accidental breaking changes

What’s included

New functionality

• Export-IdlePlanObject (IdLE.Core): Core implementation that maps an internal LifecyclePlan to the canonical export DTO.
• Export-IdlePlan (IdLE meta module): User-facing wrapper for exporting plans as JSON (string or file).

Contract specification

• docs/specs/plan-export.md
  • Normative JSON schema definition
  • Explicit versioning via schemaVersion
  • Clear separation between contract data and engine internals

Tests

• Golden / snapshot test to lock the JSON contract
• Fixture-based expected output under tests/fixtures/plan-export/expected/
• File-output test using TestDrive: (no repo pollution)
• Uses the existing _testHelpers.ps1 consistently

Design decisions (intentional)

• Deterministic output
  • No timestamps in the exported plan
  • No engine.version field (avoids noise on version bumps)
  • Empty strings normalized to null
• Clear responsibility split
  • Core: contract mapping (Export-IdlePlanObject)
  • Meta module: UX wrapper (Export-IdlePlan)
• Contract-first
  • Compatibility is tracked via schemaVersion
  • Internal plan shape can evolve without breaking exports

Example

$plan | Export-IdlePlan
$plan | Export-IdlePlan -Path ./artifacts/plan.json

Issues

• Closes Plan export as JSON - machine-readable plan artifact #9

[chatgpt-codex-connector]

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