feat(lnd): capture aezeed at wallet init + encrypted backup + reveal UI

- aezeed words are now captured at BOTH wallet-init paths and stored
  encrypted (Argon2 + ChaCha20-Poly1305, per-node wallet secret) at
  identity/lnd_aezeed.enc; ack marker cleared when a wallet is recreated
- lnd.init-wallet-from-seed was posting seed_entropy to /v1/initwallet,
  which is a GenSeed field — the wallet was never actually derived from
  the master seed; now GenSeed(entropy) → InitWallet(words)
- new RPCs: lnd.seed-backup-status / lnd.seed-reveal (password + 2FA
  gated, same as seed.reveal via shared verify_reveal_auth) /
  lnd.seed-backup-ack
- LND app detail page: Lightning-seed card with first-launch backup
  prompt, tap-to-reveal modal, 'I've backed it up' acknowledgment

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

core/archipelago/src/container/lnd.rs

@@ -505,11 +505,11 @@ async fn init_wallet_via_rest() -> Result<()> {
         anyhow::bail!("LND genseed returned no seed words");
     }
 
-    let wallet_password =
-        base64::engine::general_purpose::STANDARD.encode(ensure_wallet_password().await?);
+    let node_secret = ensure_wallet_password().await?;
+    let wallet_password = base64::engine::general_purpose::STANDARD.encode(&node_secret);
     let req = InitWalletRequest {
         wallet_password,
-        cipher_seed_mnemonic: seed.cipher_seed_mnemonic,
+        cipher_seed_mnemonic: seed.cipher_seed_mnemonic.clone(),
     };
     match post_lnd_unlocker_json::<serde_json::Value>(
         &client,
@@ -519,7 +519,14 @@ async fn init_wallet_via_rest() -> Result<()> {
     .await
     .context("initializing LND wallet")?
     {
-        UnlockerResponse::Value(_) => {}
+        UnlockerResponse::Value(_) => {
+            persist_aezeed_backup(
+                std::path::Path::new(ARCHY_DATA_DIR),
+                &seed.cipher_seed_mnemonic,
+                &node_secret,
+            )
+            .await;
+        }
         UnlockerResponse::WalletAlreadyExists => {
             unlock_existing_wallet().await?;
         }
@@ -528,6 +535,32 @@ async fn init_wallet_via_rest() -> Result<()> {
     Ok(())
 }
 
+/// Persist the just-created wallet's aezeed words encrypted with the per-node
+/// secret so they can be revealed later (`lnd.seed-reveal`). aezeed cannot be
+/// re-derived after init, so this is the only capture point on the unattended
+/// boot path. Best-effort: a failed backup must not fail wallet creation.
+pub(crate) async fn persist_aezeed_backup(
+    data_dir: &std::path::Path,
+    words: &[String],
+    node_secret: &str,
+) {
+    match crate::seed::save_lnd_aezeed_encrypted(data_dir, words, node_secret).await {
+        Ok(()) => {
+            // A fresh wallet means a fresh seed — any previous "user backed it
+            // up" acknowledgment no longer applies.
+            crate::seed::clear_lnd_aezeed_acknowledged(data_dir).await;
+            tracing::info!("[lnd] aezeed backup saved (encrypted with per-node secret)");
+        }
+        Err(e) => tracing::warn!("[lnd] failed to save aezeed backup: {e:#}"),
+    }
+}
+
+/// The per-node wallet password if one has been persisted; never generates.
+/// Used by the reveal RPC to decrypt the aezeed backup.
+pub(crate) async fn wallet_password_if_exists() -> Option<String> {
+    read_wallet_password().await
+}
+
 async fn get_lnd_unlocker_json<T: for<'de> Deserialize<'de>>(
     client: &reqwest::Client,
     path: &str,