feat: BIP-39 master seed for unified key derivation

Replace fragmented random key generation with a single 24-word BIP-39
mnemonic that deterministically derives all node keys: Ed25519 (DID),
secp256k1 (Nostr/Bitcoin), BIP-84 xprv (Bitcoin Core), and LND aezeed
entropy. New onboarding flow: seed generate → word verification → identity
naming. Restore path enabled via 24-word entry. Includes seed RPC handlers,
mock backend support, LND/Bitcoin Core wallet-from-seed integration, and
UI polish across settings and discover views.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/archipelago/src/credentials/types.rs

@@ -56,6 +56,26 @@ pub struct CredentialStatusEntry {
     pub status: String,
 }
 
+/// Status of a verifiable credential.
+#[allow(dead_code)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum CredentialStatus {
+    Active,
+    Revoked,
+    Expired,
+}
+
+impl std::fmt::Display for CredentialStatus {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Active => write!(f, "active"),
+            Self::Revoked => write!(f, "revoked"),
+            Self::Expired => write!(f, "expired"),
+        }
+    }
+}
+
 /// Stored credentials index.
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
 pub struct CredentialStore {