chore: make cryptocurrency dependencies optional to avoid build issues

requirements-crypto.txt

+# Optional cryptocurrency payment dependencies
+# These require system libraries: pkg-config, libsecp256k1-dev
+# Install system dependencies first:
+#   Ubuntu/Debian: sudo apt-get install pkg-config libsecp256k1-dev build-essential
+#   RHEL/CentOS: sudo yum install pkgconfig libsecp256k1-devel gcc
+#   Alpine: sudo apk add pkgconfig libsecp256k1-dev gcc musl-dev
+
+bip32>=3.4
+mnemonic>=0.20
+bitcoinlib>=0.6.14
+web3>=6.0.0
+eth-account>=0.9.0

requirements.txt

@@ -27,12 +27,11 @@ flask
 curl_cffi>=0.5.0  # Optional: For TLS fingerprinting to bypass Cloudflare (Claude OAuth2)
 paypalrestsdk  # PayPal REST API SDK
 
-# Payment system dependencies
+# Payment system dependencies (core)
 stripe>=5.0.0
 httpx>=0.24.0
 cryptography>=41.0.0
-bip32>=3.4
-mnemonic>=0.20
-bitcoinlib>=0.6.14
-web3>=6.0.0
-eth-account>=0.9.0
+
+# Cryptocurrency dependencies moved to requirements-crypto.txt (optional)
+# These require system libraries (pkg-config, libsecp256k1-dev)
+# Install with: pip install -r requirements-crypto.txt
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