Capture BSD Program Lane v0.2.1 L1 registry tranche

[mdheller]

Summary

Captures the newly uploaded BSD Program Lane v0.2.1 L1 registry tranche metadata and hash-locks all uploaded artifacts.

This PR adds:

• reports/v0.2.1/BSD_Program_Lane_v0_2_1_CAPTURE.md — manifest, tranche summary, claim boundary, registry verification, candidate lists, and remaining native-import boundary.
• reports/v0.2.1/ARTIFACTS.sha256 — SHA-256 lockfile for all four uploaded artifacts.

Uploaded artifacts captured

BSD_Program_Lane_v0_2_1.pdf      sha256 9a058d3f464654fee3e49c00ce89b23adf0ec90680975d980440ae522f414896
bsd_registry_v021_stats.json     sha256 4cc847a7122c60f6e0e5237d43c03e4c1040efb5fdedc5eafda18e1d27bf57ef
bsd_registry_v021.csv            sha256 5cc476c1c1d6649858fc0b0a0de5433ee82df47f1dc672039ecd56e296a4346c
bsd_registry_v021.json           sha256 afe0f920625b882a36bf35d5a1490d6b24dc557484a4f860ac03ca9aba5324f4

Captured tranche result

• N_0 = 1000
• total rows: 1000
• squarefree rows: 608
• non-squarefree rows: 392
• L_nonzero: 432
• L_zero: 568
• root numbers: 503 plus / 497 minus
• C5 corrected pass: 1000 / 1000
• rank >= 2 squarefree candidates: 53

Boundary

This is a capture/control PR only. It does not certify BSD for any curve and does not run any M6 or v0.2.2 computation.

The PDF, CSV, and full JSON are hash-locked here but still require a binary-capable/native import path for exact repository-native storage. The small stats JSON was read and summarized, but the connector path blocked a direct JSON-file create for the full stats object. The hash lock preserves identity until native import.

Related: #1.