chore(security): enhance environment configuration, CI workflows, and wallet daemon with security improvements

- Restructure .env.example with security-focused documentation, service-specific environment file references, and AWS Secrets Manager integration
- Update CLI tests workflow to single Python 3.13 version, add pytest-mock dependency, and consolidate test execution with coverage
- Add comprehensive security validation to package publishing workflow with manual approval gates, secret scanning, and release

migration_examples/config_migration.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+"""
+Configuration Migration Example
+
+Shows how to migrate configuration to use the new abstraction layer.
+"""
+
+# BEFORE (CUDA-specific config)
+# cuda_config = {
+#     "lib_path": "./liboptimized_field_operations.so",
+#     "device_id": 0,
+#     "memory_limit": 8*1024*1024*1024
+# }
+
+# AFTER (Backend-agnostic config)
+from gpu_acceleration import ZKOperationConfig, GPUAccelerationManager, ComputeBackend
+
+# Configuration for any backend
+config = ZKOperationConfig(
+    batch_size=2048,
+    use_gpu=True,
+    fallback_to_cpu=True,
+    timeout=60.0,
+    memory_limit=8*1024*1024*1024  # 8GB
+)
+
+# Create manager with specific backend
+gpu = GPUAccelerationManager(backend=ComputeBackend.CUDA, config=config)
+gpu.initialize()
+
+# Or auto-detect with config
+from gpu_acceleration import create_gpu_manager
+gpu = create_gpu_manager(
+    backend="cuda",  # or None for auto-detect
+    batch_size=2048,
+    fallback_to_cpu=True,
+    timeout=60.0
+)