ESP32 USB/NIP-46 Signer

Daily-use connected ESP32-S3 signer with USB/display review and bridged NIP-46 inputs.

Boundaries

The companion handles NIP-46 bridge decisions via nsealr nip46 decide; the device receives already-decrypted, validated signing requests.
USB transport uses bounded frames with request-bound capture checks. Bring-up is covered by nsealr serial-line exchange.
Smoke evidence: companion-to-device serial smoke, sign-event-disabled smoke, firmware protocol evidence, Unicode fallback tracking.
signing_disabled until hardening gates pass; approvals are bound to approval_digest.

Feature	Target	Current	Contract
`request_validation_v0`	required	implemented	`signing-request-v0+implementation-limits-v0+invalid-vectors`
`nostr_event_review_universal`	required	implemented	`trusted-review-v0+review-detail-pages-v0`
`review_detail_pages`	optional	implemented	`review-detail-pages-v0`
`approval_digest_binding`	required	implemented	`approval-digest-v0`
`physical_approval`	required	partial	`physical-approval-v0`
`sign_event_bip340`	required	disabled_until_gates_pass	`nostr-sign-event-bip340-v0`
`serial_usb_transport`	required	implemented	`serial-usb-transport-v0`
`nip46_decrypted_bridge`	required	partial	`nip46-decrypted-bridge-v0`
`scoped_policy_automation`	required	planned	`scoped-policy-automation-v0`
`persistent_secret_custody`	required	planned	`persistent-secret-custody-v0`
`secure_boot_hardening`	required	planned	`firmware-boot-hardening-v0`
`response_verification`	required	implemented	`signed-response-verification-v0`
`stateless_session_custody`	forbidden	forbidden	—