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/wallet/profits.rs

@@ -53,6 +53,42 @@ pub async fn load_profits(data_dir: &Path) -> Result<ProfitsSummary> {
     Ok(summary)
 }
 
+/// Save profits summary to disk.
+#[allow(dead_code)]
+pub async fn save_profits(data_dir: &Path, summary: &ProfitsSummary) -> Result<()> {
+    let dir = data_dir.join("wallet");
+    fs::create_dir_all(&dir)
+        .await
+        .context("Failed to create wallet directory")?;
+    let path = data_dir.join(PROFITS_FILE);
+    let content = serde_json::to_string_pretty(summary)
+        .context("Failed to serialize profits")?;
+    fs::write(&path, content)
+        .await
+        .context("Failed to write profits file")?;
+    Ok(())
+}
+
+/// Record a single content sale, updating totals and the recent entries list.
+#[allow(dead_code)]
+pub async fn record_content_sale(data_dir: &Path, amount_sats: u64, description: &str) -> Result<()> {
+    let mut summary = load_profits(data_dir).await?;
+    let entry = ProfitEntry {
+        source: ProfitSource::ContentSale,
+        amount_sats,
+        timestamp: chrono::Utc::now().to_rfc3339(),
+        description: description.to_string(),
+    };
+    summary.recent.insert(0, entry);
+    if summary.recent.len() > 100 {
+        summary.recent.truncate(100);
+    }
+    summary.content_sales_sats += amount_sats;
+    summary.total_sats = summary.content_sales_sats + summary.routing_fees_sats;
+    save_profits(data_dir, &summary).await?;
+    Ok(())
+}
+
 /// Compute a full profits summary including ecash receive transactions.
 pub async fn get_networking_profits(data_dir: &Path) -> Result<ProfitsSummary> {
     let mut summary = load_profits(data_dir).await?;