fix(contractiles): correct filename drift (Trustfille→Trustfile, Bustfile→Bustfile.a2ml)

Two drift items surfaced during 2026-04-17 contractile-layout audit:
- trust/Trustfille.a2ml had a typo (two L's in Trustfille)
- bust/Bustfile was missing the .a2ml extension

Per the contractile layout rule (one <Verb>file.a2ml per <verb>/ dir,
lowercase verb for the runner), both needed correction. No code paths
reference either name, so the rename is safe.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath