foundation_keychain — Bitwarden-compatible vault + SSH key provisioning (spec-57).
WHY: Provide a self-hosted, Bitwarden API-compatible secrets vault with
SSH key provisioning, built entirely on foundation_db (storage) and
foundation_auth (JWT/TOTP/PBKDF2/middleware). No custom traits, no
reinvented crypto, no tokio.
WHAT: Bitwarden HTTP API (~150 routes), portable domain models, SignalR MessagePack notifications, and SSH key generation + at-rest encryption.
HOW: core/ holds portable domain logic. server/ holds platform-gated
HTTP entry points (Workers via foundation_deployment_cloudflare, native via
foundation_http). All storage through foundation_db traits; all auth
through foundation_auth.