Fix import_secrets_config to actually process the bitcoin config

Upstream Cake declares bitcoinConfigPath + bitcoinOutputPath at the top of
tool/import_secrets_config.dart but never references them in the function
body. Result: every fresh clone runs 'dart run tool/generate_new_secrets.dart'
and ends up with cw_evm/cw_solana/cw_tron/cw_nano/.secrets.g.dart populated
but cw_bitcoin/lib/.secrets.g.dart still missing — and the Linux build
fails on the cw_bitcoin import that needs breezApiKey.

Plumb bitcoin into the pipeline the same way the others are. The bitcoin
JSON config (tool/.bitcoin-secrets-config.json) only has breezApiKey today,
which we populate as an empty string since Lightning is disabled.

tool/import_secrets_config.dart

@@ -49,6 +49,15 @@ Future<void> importSecretsConfig() async {
   final nanoOutput =
       nanoInput.keys.fold('', (String acc, String val) => acc + generateConst(val, nanoInput));
 
+  // Hash Wallet: upstream Cake declares bitcoinConfigPath/bitcoinOutputPath
+  // but never processes them, leaving cw_bitcoin/lib/.secrets.g.dart missing
+  // and the build broken on a fresh clone. Add it to the pipeline.
+  final bitcoinOutputFile = File(bitcoinOutputPath);
+  final bitcoinInput =
+      json.decode(File(bitcoinConfigPath).readAsStringSync()) as Map<String, dynamic>;
+  final bitcoinOutput =
+      bitcoinInput.keys.fold('', (String acc, String val) => acc + generateConst(val, bitcoinInput));
+
   if (outputFile.existsSync()) {
     await outputFile.delete();
   }
@@ -78,4 +87,10 @@ Future<void> importSecretsConfig() async {
   }
 
   await nanoOutputFile.writeAsString(nanoOutput);
+
+  if (bitcoinOutputFile.existsSync()) {
+    await bitcoinOutputFile.delete();
+  }
+
+  await bitcoinOutputFile.writeAsString(bitcoinOutput);
 }