feat(wallet): Ark protocol support via barkd sidecar

barkd (Ark wallet daemon, pinned 0.3.0, checksum-verified release binary)
packaged as an installable app; thin HTTP bridge in wallet/ark_client.rs
mirrors the fedimint_client pattern — the bark SDK stays out of the node
binary. wallet.ark-* RPCs cover status/balance/address/send/invoice/
board/offboard/history/configure; Ark movements merge into the unified
ecash history (kind="ark") and spendable Ark sats into total_sats.
Signet defaults (Second's public Ark server) until Ark matures.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/archipelago/src/server.rs

@@ -1590,6 +1590,7 @@ fn fallback_package_port(app_id: &str) -> Option<u16> {
     match app_id {
         "fedimint" | "fedimintd" => Some(8175),
         "fedimint-clientd" => Some(8178),
+        "barkd" => Some(3535),
         "filebrowser" => Some(8083),
         "indeedhub" => Some(7778),
         "nginx-proxy-manager" => Some(8081),