Add Bitcoin wallet withdraw and seed reveal UI in CMS.

Wire admin actions to the backend API with client-side address validation and configurable max fee rate.

cms/src/utils/bitcoin/isBitcoinAddress.ts

@@ -0,0 +1,28 @@
+import type { BitcoinNetwork } from '@/types/bitcoinWallet/BitcoinNetwork';
+
+// Soft validation only: prefix/length checks to reject obvious garbage and wrong-network
+// addresses early. Checksums and spendability are validated by Electrum on payto.
+const BASE58 = '[1-9A-HJ-NP-Za-km-z]';
+
+const NETWORK_ADDRESS_PATTERNS: Record<BitcoinNetwork, RegExp[]> = {
+    mainnet: [
+        new RegExp(`^1${BASE58}{25,34}$`),
+        new RegExp(`^3${BASE58}{25,34}$`),
+        /^bc1[a-z0-9]{25,87}$/
+    ],
+    testnet4: [
+        new RegExp(`^[mn]${BASE58}{25,34}$`),
+        new RegExp(`^2${BASE58}{25,34}$`),
+        /^(?:tb1|bcrt1)[a-z0-9]{25,87}$/
+    ]
+};
+
+export const isBitcoinAddress = (value: unknown, network: BitcoinNetwork): boolean => {
+    if (typeof value !== 'string') {
+        return false;
+    }
+
+    const trimmed = value.trim();
+
+    return NETWORK_ADDRESS_PATTERNS[network].some(pattern => pattern.test(trimmed));
+};