M6 engine: wave-loop composition per verified design (build only) (#173)

* Build M6 projection engine adapters

Compose the verified annual loop, injected marital and household state, cutoff refits, fixed-weight support, and reproduction-mode disability coverage.

Co-Authored-By: Codex gpt-5.6-sol <noreply@openai.com>

* Implement M6 forward earnings generator

Fit the pinned <=2014 forward conditional-rank chain on ages 25-64, project NAWI from the 2005-2014 OLS, and preserve generated biennial memory through frame state.

Wire the fitted generator as the refit-bundle default while retaining the explicit external earnings seam.

Co-Authored-By: Codex gpt-5.6-sol <noreply@openai.com>

---------

Co-authored-by: Codex gpt-5.6-sol <noreply@openai.com>

Author: MaxGhenis

src/populace_dynamics/engine/__init__.py

@@ -0,0 +1,89 @@
+"""M6 annual projection engine and cutoff-refit adapters."""
+
+from populace_dynamics.engine.assembly import (
+    CertifiedEngineInputs,
+    assemble_period_modules,
+)
+from populace_dynamics.engine.composition import (
+    CompositionDiagnostics,
+    CompositionRngs,
+    RecertificationResult,
+    check_candidate9_recertification,
+    composition_rngs_from_registry,
+    simulate_candidate9_injected,
+    simulate_candidate9_internal_reference,
+)
+from populace_dynamics.engine.disability import simulate_reproduction
+from populace_dynamics.engine.forward_earnings import (
+    ForwardEarningsGenerator,
+    fit_forward_earnings,
+)
+from populace_dynamics.engine.loop import (
+    MaritalStepResult,
+    PeriodContext,
+    PeriodModules,
+    ProjectionEngine,
+    ProjectionResult,
+    SyntheticPersonIdAllocator,
+)
+from populace_dynamics.engine.marital import (
+    simulate_marital_step,
+    simulate_maternal_births,
+)
+from populace_dynamics.engine.refit import (
+    BOUNDARY_YEAR,
+    M6RefitBundle,
+    M6RefitInputs,
+    refit_m6_components,
+)
+from populace_dynamics.engine.rng import (
+    ProjectionModule,
+    ProjectionRNGRegistry,
+)
+from populace_dynamics.engine.steps import (
+    AgeSexMortalityModel,
+    ClaimingSchedule,
+    FertilityDraws,
+)
+from populace_dynamics.engine.support import (
+    EvaluationMode,
+    PresenceBasis,
+    StartWaveWeightSnapshot,
+    prepare_evaluation_support,
+)
+
+__all__ = [
+    "BOUNDARY_YEAR",
+    "AgeSexMortalityModel",
+    "CertifiedEngineInputs",
+    "ClaimingSchedule",
+    "CompositionDiagnostics",
+    "CompositionRngs",
+    "EvaluationMode",
+    "FertilityDraws",
+    "ForwardEarningsGenerator",
+    "M6RefitBundle",
+    "M6RefitInputs",
+    "MaritalStepResult",
+    "PeriodContext",
+    "PeriodModules",
+    "PresenceBasis",
+    "ProjectionEngine",
+    "ProjectionModule",
+    "ProjectionRNGRegistry",
+    "ProjectionResult",
+    "RecertificationResult",
+    "StartWaveWeightSnapshot",
+    "SyntheticPersonIdAllocator",
+    "assemble_period_modules",
+    "check_candidate9_recertification",
+    "composition_rngs_from_registry",
+    "prepare_evaluation_support",
+    "fit_forward_earnings",
+    "refit_m6_components",
+    "simulate_candidate9_injected",
+    "simulate_candidate9_internal_reference",
+    "simulate_marital_step",
+    "simulate_maternal_births",
+    "simulate_reproduction",
+]