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

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

step-04-signer/README.md

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+# Step 4 — Derivation / Signer
+
+- **types-signer.ts** — Signer interface (Ethereum-style: getAddress, signTransaction, signPersonalMessage). Use as-is for EVM/Chain 138.
+- **getAddress.ts** — getAddress resolver using `@ledgerhq/coin-framework` (GetAddressFn, SignerContext, GetAddressOptions). Register in live-common family setup.
+
+**CLI check (after currency is added):**
+```bash
+ledger-live getAddress --currency defi_oracle_meta_mainnet --path "44'/60'/0'/0/0" --derivationMode ""
+```
+Or with ethereum currency and chainId in config:
+```bash
+ledger-live getAddress --currency ethereum --path "44'/60'/0'/0/0" --derivationMode ""
+```
+
+Derivation for Chain 138: **44'/60'/0'/0/0** (standard EVM BIP44).

step-04-signer/getAddress.ts

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+/**
+ * Step 4 — Derivation / Signer: getAddress resolver
+ * Target: ledger-live libs/coin-modules/coin-*/src/signer/getAddress.ts
+ *
+ * Uses @ledgerhq/coin-framework getAddressWrapper. For Ethereum family the
+ * existing Ethereum getAddress resolver applies; ensure currency/chainId 138
+ * is used when resolving for Defi Oracle Meta Mainnet.
+ *
+ * Example resolver shape (adapt to your coin-framework version):
+ */
+
+import type { GetAddressFn } from "@ledgerhq/coin-framework/bridge/getAddressWrapper";
+import type { SignerContext } from "@ledgerhq/coin-framework/signer";
+import type { GetAddressOptions } from "@ledgerhq/coin-framework/derivation";
+import type { EthereumAddress, EthereumSigner } from "./types-signer";
+
+const resolver = (
+  signerContext: SignerContext<EthereumSigner, EthereumAddress>
+): GetAddressFn => {
+  return async (deviceId: string, { path, verify }: GetAddressOptions) => {
+    const address = (await signerContext(deviceId, (signer) =>
+      signer.getAddress(path, verify)
+    )) as EthereumAddress;
+    return {
+      address: address.address,
+      publicKey: address.publicKey,
+      path,
+    };
+  };
+};
+
+export default resolver;

step-04-signer/types-signer.ts

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+/**
+ * Step 4 — Derivation / Signer: types
+ * Target: ledger-live libs/coin-modules/coin-*/src/types/signer.ts
+ * For EVM we use the same as Ethereum; Chain 138 uses path 44'/60'/0'/0/0.
+ */
+
+export type EthereumAddress = {
+  address: string;
+  publicKey: string;
+  returnCode: number;
+};
+
+export type EthereumSignature = {
+  signature: Buffer | null;
+  returnCode: number;
+};
+
+export interface EthereumSigner {
+  getAddress(path: string, display?: boolean): Promise<EthereumAddress>;
+  signTransaction(path: string, rawTxHex: string): Promise<EthereumSignature>;
+  signPersonalMessage(path: string, messageHex: string): Promise<EthereumSignature>;
+}