feat(transport): get_machine_config RPC — server-delivered machine config (#41)

A paired ATM pulls its operator pubkey + fee config over the already-
authenticated kind-21000 transport, instead of the operator pubkey being
provisioned into the machine's .env and the fee config learned only from an
operator-signed kind-30078 broadcast. This lets a seed-only machine (blank
.env, scanned spire-seed) leave "awaiting configuration" with zero per-machine
provisioning — closing the gap surfaced by bitspire#70. Client half: bitspire#71.

The transport is already per-machine authenticated (the ATM signs with its
bunker-minted spire key == dca_machines.machine_npub), so the handler resolves
the exact machine → operator from the verified request.sender_pubkey — same
lookup as cashin_transport, no client-supplied trust — and returns only the
caller's own config. Returns {operator_pubkey, fee_config, fiat_code,
machine_npub, wallet_id, created_at}; fee_config is None until the operator has
a super-config. Reuses build_fee_payload + get_account; AUTH_ACCOUNT; registers
soft-failing (older lnbits) like the roster hook. kind-30078 push stays
dual-run for live mid-run updates.

6 tests; full suite 235 pass; black + ruff clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

__init__.py

@@ -6,6 +6,7 @@ from loguru import logger
 
 from .cashin_transport import register_create_withdraw_rpc
 from .crud import db
+from .machine_config_transport import register_machine_config_rpc
 from .nostr_transport_roster import register_with_lnbits as register_roster_with_lnbits
 from .tasks import wait_for_cassette_state_events, wait_for_paid_invoices
 from .views import spirekeeper_generic_router
@@ -62,6 +63,11 @@ def spirekeeper_start():
     # server-side, never client-supplied. Soft-fails if `register_rpc` isn't
     # exposed by this lnbits.
     register_create_withdraw_rpc()
+    # Server-delivered machine config (#41 / bitspire#70 P1): register the
+    # get_machine_config RPC so a paired ATM pulls its operator pubkey + fee
+    # config over the transport, leaving "awaiting configuration" with no
+    # per-machine env provisioning. Soft-fails if register_rpc isn't exposed.
+    register_machine_config_rpc()
 
 
 __all__ = [