fix: delete compliance-pipeline/'s hardcoded 64-GUID mapper (B6)

[warrendt]

compliance-pipeline/ was a fourth, fully standalone mapping stack with its own policy_mapper.py hardcoding a 64-GUID menu (32 overlapping the backend's pre-B1 34-GUID menu) — the same defect B1 fixed in the backend pipeline, at larger scale, in a copy nothing in app/ imports or references.

Decision: deleted, not delegated

Per explicit direction: hardcoding a policy shortlist voids the reason the AI mapping engine exists — a curated list caps recall at whatever its author thought of, against a catalogue of 2,467 shipped definitions.

Confirmed before deleting: no code or test under app/ (backend, frontend, or tests) imports or references compliance-pipeline/ — it's a fully standalone CLI tool with its own requirements.txt and entry point (pipeline.py), never sharing a runtime with the backend. Reworking it to delegate to AIMappingService would mean building and maintaining a second integration surface into the shared mapping engine for a tool nothing else depends on, so it's deleted outright:

• pipeline.py, policy_mapper.py, control_extractor.py, pdf_extractor.py, initiative_builder.py, validator.py, models.py, config.py, its requirements.txt, .env.template, and README.md.
• Its two remaining references in README.md and docs/FUNCTIONAL_SPEC.md (## 8. Known limitations) removed.

There is now exactly one mapping engine in the repository (AIMappingService), reached by both the services path and the pipeline path (B1).

Testing

Re-ran the pipeline/mapping/initiative test groups to confirm nothing depended on the deleted directory — 91 passed, no regressions.