feat: import BSD program lane v0.1 skeleton; declare Heller-Godel dependency

[mdheller]

Summary

Adds the BSD Program Lane v0.1 structural skeleton and declares canonical dependency on SocioProphet/Heller-Godel @ 988307215ad38ccb16514311222184a1b757752b for framework/PFK surfaces.

This PR is explicit about source state: the full Drive PDF text is not imported here. The file docs/program-spec/bsd-program-lane-v0_1.md is a structural skeleton based on known v0.1 program shape. A future source-import PR with Drive/PDF access should replace the skeleton with full extracted markdown.

What this PR does

1. Adds DEPENDENCIES.md pinning Heller-Godel @ 988307215ad38ccb16514311222184a1b757752b.
2. Adds docs/program-spec/bsd-program-lane-v0_1.md as a structural skeleton, not a full PDF import.
3. Adds workstream skeletons A-F under docs/workstream-{a..f}/.
4. Updates README.md to surface the Heller-Godel/PFK dependency and BSD lane skeleton.
5. Adds tests/test_pfk_dependency.py to validate dependency pin, canonical PFK path resolution, and workstream skeleton presence.
6. Adds .github/workflows/bsd-proof-program-pfk-dependency.yml, checking out Heller-Godel at the pinned commit.

Actual-state note

bsd-proof-program is not a two-commit stub anymore. Current main already contains M6 v0.3.2 pre-execution scaffolding and a root-number/Selmer readout-basis barrier note. This PR preserves that state and adds dependency/workstream scaffolding around it.

Scope discipline

This PR does not change M6 discipline:

• no descent computation;
• no second-point search extension;
• no dataset promotion;
• no M6.7 validation gate execution;
• no final M6.8 report;
• no change to v0.5 row state;
• no BSD proof claim;
• no row promotion;
• no finite-Sha assumption;
• no parity theorem use for M6 promotion.

Cited upstream surfaces

• HG-MTH-005 — Universal Bridge formal specification, method-grade only.
• HG-MTH-009 — BSD-domain extension reserved, not yet drafted.
• PFK-SCHEMA-001..004 — canonical schemas.
• A-PFK-* — PFK operational anti-seeds.
• A-MTH-001 — Universal Bridge does not transfer proofs.

What this PR does not do

• Does not import the full Drive PDF text.
• Does not promote any claim grade.
• Does not constitute BSD progress.
• Does not produce descriptive-grade or theorem-grade claims.
• Does not advance Clay proximity above 0-5%.
• Does not draft HG-MTH-009; that remains upstream Heller-Godel work.
• Does not emit Event-IR receipts.

CI gating

Expected checks:

• existing validate workflow;
• new bsd-proof-program PFK Dependency Validation workflow.

The new workflow validates that Heller-Godel canonical PFK paths resolve from the pinned commit under HELLER_GODEL_ROOT.

Follows from

• Heller-Godel PR #67 — PFK registry expansion @ 988307215ad38ccb16514311222184a1b757752b.
• Heller-Godel PR #66 — HG-MTH-005 @ 56ce7adaab8b9f09f25900bce653a5ceaf417eb6.
• np-program PR #35 — migration @ ec2962af7f4aa841973bf24246f53aa95b280037.
• hodge-program-proof PR #19 — migration @ c60198af4e319ba2bc56306bd9753acec9b6a68a.
• Heller-Winters PR #40 — pin cleanup @ 85849a4638c07c09e09204fe9305e095b70c9c22.