feat(shared): lift recovery-code primitives into shared crypto module

packages/shared/src/crypto/recoveryCode.ts

@@ -0,0 +1,22 @@
+import { getCryptoBackend } from './backend';
+
+export const RECOVERY_ALPHABET = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
+export const RECOVERY_CODE_LEN = 24;
+
+export async function generateRecoveryCode(): Promise<string> {
+  const raw = getCryptoBackend().randomBytes(RECOVERY_CODE_LEN);
+  let out = '';
+  for (let i = 0; i < raw.length; i++) {
+    out += RECOVERY_ALPHABET[raw[i]! % RECOVERY_ALPHABET.length];
+    if ((i + 1) % 6 === 0 && i !== raw.length - 1) out += '-';
+  }
+  return out;
+}
+
+export function normalizeRecoveryCode(input: string): string {
+  return input
+    .toUpperCase()
+    .split('')
+    .filter((c) => RECOVERY_ALPHABET.includes(c))
+    .join('');
+}