Add full Chain 138 integration: 8 steps, chain spec, app-ethereum config, docs

Co-authored-by: Cursor <cursoragent@cursor.com>

step-03-coin-module/network-explorer.ts

@@ -0,0 +1,75 @@
+/**
+ * Step 3 — Coin module: network layer (explorer/RPC wrapper)
+ * Target: ledger-live libs/coin-modules/coin-ethereum (or coin-defi_oracle_meta) src/network/
+ *
+ * Wraps Chain 138 RPC and Blockscout for sync, history, fees. Use in bridge.
+ */
+
+const RPC_URL = "https://rpc-http-pub.d-bis.org";
+const EXPLORER_API = "https://explorer.d-bis.org/api";
+
+export async function getLastBlock(): Promise<number> {
+  const res = await fetch(RPC_URL, {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({ jsonrpc: "2.0", id: 1, method: "eth_blockNumber", params: [] }),
+  });
+  const data = await res.json();
+  return parseInt(data.result, 16);
+}
+
+export async function getBalance(address: string): Promise<string> {
+  const res = await fetch(RPC_URL, {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({
+      jsonrpc: "2.0",
+      id: 1,
+      method: "eth_getBalance",
+      params: [address, "latest"],
+    }),
+  });
+  const data = await res.json();
+  return data.result ?? "0x0";
+}
+
+export async function getTransactionCount(address: string): Promise<number> {
+  const res = await fetch(RPC_URL, {
+    method: "POST",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify({
+      jsonrpc: "2.0",
+      id: 1,
+      method: "eth_getTransactionCount",
+      params: [address, "latest"],
+    }),
+  });
+  const data = await res.json();
+  return parseInt(data.result ?? "0x0", 16);
+}
+
+/**
+ * Explorer: get transactions for address.
+ * Blockscout REST v2: GET /api/v2/addresses/{address_hash}/transactions
+ * Response: { items: Tx[], next_page_params?: { block_number, index, items_count } }
+ */
+const EXPLORER_API_V2 = "https://explorer.d-bis.org/api/v2";
+
+export async function getAddressTransactions(
+  address: string,
+  params?: { block_number?: number; index?: number; items_count?: number }
+): Promise<{ items: unknown[]; next_page_params?: { block_number: number; index: number; items_count: number } }> {
+  let url = `${EXPLORER_API_V2}/addresses/${encodeURIComponent(address)}/transactions`;
+  if (params?.block_number != null && params?.index != null && params?.items_count != null) {
+    url += `?block_number=${params.block_number}&index=${params.index}&items_count=${params.items_count}`;
+  }
+  const res = await fetch(url);
+  if (!res.ok) return { items: [] };
+  const data = await res.json();
+  return {
+    items: data.items ?? [],
+    next_page_params: data.next_page_params,
+  };
+}
+
+export { RPC_URL, EXPLORER_API, EXPLORER_API_V2 };