Feature: refactor FEMIC around named pipelines built from recipe sequences

[gparadis]

Summary

Refactor FEMIC away from the legacy monolithic 00_data-prep.py, 01a_run-tsa.py, and 01b_run-tsa.py mental model toward a named-pipeline system built from reusable recipes, overlays, and runbook-defined restart seams.

Why

FEMIC is already moving toward recipe-driven execution, but the overall workflow model is still fragmented across legacy stage scripts and ad hoc runtime seams. We want a simpler and more flexible user-facing concept:

• FEMIC runs a named pipeline;
• each pipeline is just a sequence of named recipes;
• recipes can come from the system registry, user-contributed registries, or local registries;
• pipelines can be customized with overlays and overrides; and
• model instances become reproducible because their runbooks describe exactly which pipeline and recipe sequence to execute.

This should preserve recent recipe-based work rather than invalidate it.

Scope of the umbrella

Track the larger architectural shift needed to support:

• named pipeline registries;
• recipe-sequence execution as the primary workflow model;
• restart seams and canonical checkpoint contracts inside pipelines;
• downstream recipes that can target Patchworks, ws3, reporting, scenario sets, indicator banks, and other extensible workflow units.

Child workstreams

• #164 closed: explicit AFLB -> strata/AU/yield -> THLB interruption seam inside the THLB workflow.
• #167 active: define named pipeline registry and runbook contracts.
• #168 closed: implement the first named-pipeline proof runner from runbooks.
• #169 active: validate TSA29 strict named pipeline against the locked-chain contract.

Rollout note

• #168 proved orchestration.
• #169 proves reproducibility against the validated strict contract.

Constraints

• This is an umbrella/architecture issue, not one giant implementation ticket.
• Child issues should stay narrowly scoped and executable.
• The design should remain consistent with the recipe-based work already completed in the TSA29 THLB reconciliation lane.

[gparadis]

Initial child issue for the first concrete execution seam under this umbrella: #164 (pause THLB at AFLB, compile strata/AUs/yield artifacts, then resume downstream THLB).