feat(modularization): Decompose Monolithic Modules (supervisor.py & quality_plane.py)

[sdageltc]

Summary & Motivation

During recent architecture audits, we noted that orchestrator/supervisor.py (~1,790 lines) and orchestrator/quality_plane.py (~1,100 lines) handle multiple cross-cutting responsibilities within single files. While their internal cohesion is strong, modularizing auxiliary functions into dedicated sub-packages will significantly improve readability, simplify unit testing, and reduce cognitive load for new contributors.

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Proposed Refactoring Plan

1. orchestrator/supervisor.py -> orchestrator/supervisor/ Package:
   • supervisor/core.py: The core state machine and event loop (execute_plan, _execute_single_contract).
   • supervisor/recovery.py: State graph recovery, checkpoint hydration, and orphan lease recovery.
   • supervisor/reporting.py: Console summary formatting (_print_run_summary), result aggregation.
   • supervisor/cleanup.py: Artifact directory cleanup and helper file pruning.
2. orchestrator/quality_plane.py -> orchestrator/qc/ Package:
   • qc/lenses.py: Individual lens evaluators (Spec, Safety, Performance, Regression).
   • qc/aggregator.py: Verdict weighting, panel majority calculations, and overrule defense parsing.
3. Public API Invariance:
   • Keep from orchestrator.supervisor import Supervisor and from orchestrator.quality_plane import QualityPlane fully backward-compatible via __init__.py re-exports.

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Key Files

• orchestrator/supervisor.py
• orchestrator/quality_plane.py
• orchestrator/__init__.py

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Acceptance Criteria

• All 1,122 existing unit and integration tests continue to pass 100% green without modification.
• File sizes for individual modules remain under 500 lines.
• Strict type annotations and zero circular import cycles.
• Clean re-exports maintaining complete backward compatibility.