chore(contractiles): reconcile three overlapping layouts + add INDEX.a2ml

[hyperpolymath]

Problem

panic-attack currently carries three overlapping contractile representations:

1. .machine_readable/*.contractile — flat files (ADJUST, INTENT, MUST, TRUST).
2. .machine_readable/contractiles/{adjust,bust,dust,trust}/ — partial trident (Xfile.a2ml + x.ncl).
3. root contractiles/{intend,must,trust}/ — Xfile.a2ml; consumed by contractile gen-just (per the contractile.just header).

This drifts from the echidna/standards shape, which is .machine_readable/contractiles/<verb>/ trident (Xfile.a2ml + x.ncl + x.k9.ncl + x.manifest.a2ml) registered in .machine_readable/contractiles/INDEX.a2ml, plus _base.ncl.

Missing vs standard

• INDEX.a2ml registry + _base.ncl schema.
• Full trident (x.k9.ncl, x.manifest.a2ml) for each verb.
• BUST / DUST verbs absent from some representations; MUST / INTEND not consistent across all three.

Blocker

The authoritative docs/CONTRACTILE-SPEC.adoc lives in hyperpolymath/standards (referenced by echidna's INDEX.a2ml), which isn't reachable from the working session. Reconciling "to standard" needs that spec and a decision on the canonical location — note that contractile gen-just reads the root contractiles/, so changing the layout requires regenerating contractile.just.

Proposed plan

1. Pick the canonical location (likely .machine_readable/contractiles/<verb>/ trident, matching echidna).
2. Migrate/dedupe the other two representations into it.
3. Add INDEX.a2ml + _base.ncl modeled on echidna's (v2.0.0, 6-verb trident).
4. Regenerate contractile.just.

Reference

/home/user/echidna/.machine_readable/contractiles/INDEX.a2ml (v2.0.0). Deferred from the 2026-06-04 close-out session.

https://claude.ai/code/session_01K2TJLeQSyz4tpydZ18aRcb