refactor(machine): remove dead Lightning.Pub nprofile UI (post-3d cutover)

The LP backend was deleted on dev, so VITE_LIGHTNING_PUB_PUBKEY /
config.lightningPubPubkey are never set — the "add this ATM's node to your
wallet" nprofile QR (IdleView dev button + overlay, SupportView ShockWallet
card + deep-link) rendered empty, and the LP fields in RuntimeConfig
(lightningPubPubkey/lightningPubApiUrl/extensionApiUrl) were never populated.
Remove them. The concept has no clean LNbits analog (the ATM is a cash↔LN
gateway, not a node customers peer with) — tracked as a fresh feature request
on lnbits. ShockWallet stays listed as a downloadable wallet (plain URL).

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

apps/machine/electron/preload.ts

@@ -17,10 +17,6 @@ export interface RuntimeConfig {
   relayUrl: string
   /** LNbits nostr-transport server pubkey (hex, 64 chars). */
   lnbitsServerPubkey: string
-  /** Legacy LP fields — retained until 3d removes the LP backend. Optional. */
-  lightningPubPubkey?: string
-  lightningPubApiUrl?: string
-  extensionApiUrl?: string
   appId: string
   machineModel: string
   fiatCode: string