refactor: extract normalizeRecoveryParam helper function

Extract duplicate v normalization logic into a private helper method
as suggested in PR review. This improves code maintainability by
consolidating the normalization logic in one place.

Coverage thresholds adjusted slightly due to branch counting changes
from code consolidation (same code paths are tested, just counted
differently by Jest).

Author: cloudonshore

packages/keyring-eth-ledger-bridge/jest.config.js

@@ -23,10 +23,10 @@ module.exports = merge(baseConfig, {
   // An object that configures minimum threshold enforcement for coverage results
   coverageThreshold: {
     global: {
-      branches: 93.71,
-      functions: 98.16,
+      branches: 93.61,
+      functions: 98.18,
       lines: 97.75,
-      statements: 97.77,
+      statements: 97.76,
     },
   },
 });

packages/keyring-eth-ledger-bridge/src/ledger-keyring.ts

@@ -458,13 +458,7 @@ export class LedgerKeyring implements Keyring {
       );
     }
 
-    let recoveryParam = parseInt(String(payload.v), 10);
-    // Normalize: Ledger may return 0 or 1 (modern format), but signature
-    // recovery expects 27 or 28 (legacy format per EIP-191)
-    if (recoveryParam === 0 || recoveryParam === 1) {
-      recoveryParam += 27;
-    }
-    const modifiedV = recoveryParam.toString(16);
+    const modifiedV = this.#normalizeRecoveryParam(parseInt(String(payload.v), 10));
 
     const signature = `0x${payload.r}${payload.s}${modifiedV}`;
     const addressSignedWith = recoverPersonalSignature({
@@ -554,13 +548,7 @@ export class LedgerKeyring implements Keyring {
       );
     }
 
-    let recoveryParam = parseInt(String(payload.v), 10);
-    // Normalize: Ledger may return 0 or 1 (modern format), but signature
-    // recovery expects 27 or 28 (legacy format per EIP-712)
-    if (recoveryParam === 0 || recoveryParam === 1) {
-      recoveryParam += 27;
-    }
-    const recoveryId = recoveryParam.toString(16);
+    const recoveryId = this.#normalizeRecoveryParam(parseInt(String(payload.v), 10));
     const signature = `0x${payload.r}${payload.s}${recoveryId}`;
     const addressSignedWith = recoverTypedSignature({
       data,
@@ -703,4 +691,20 @@ export class LedgerKeyring implements Keyring {
   #getChecksumHexAddress(address: string): Hex {
     return getChecksumAddress(add0x(address));
   }
+
+  /**
+   * Normalizes the signature recovery parameter (v) to legacy format.
+   * Ledger devices may return v as 0 or 1 (modern format), but signature
+   * recovery expects 27 or 28 (legacy format per EIP-191/EIP-712).
+   *
+   * @param v - The recovery parameter from Ledger.
+   * @returns The normalized v value as a hex string.
+   */
+  #normalizeRecoveryParam(v: number): string {
+    let recoveryParam = v;
+    if (recoveryParam === 0 || recoveryParam === 1) {
+      recoveryParam += 27;
+    }
+    return recoveryParam.toString(16);
+  }
 }