v0.4.2 - Pluggable Executors, RBAC Gateway Differentiation & Verification

Release 0.4.2

• 4 Packaged Mediated Executors: Added \ empus-http-executor\ (HTTPS webhooks), \ empus-slack-executor\ (Slack alerts), \ empus-payment-executor\ (pluggable financial transport & money contract enforcement), and \ empus-github-executor.
• Framework Cookbooks: Added integration recipes for LangChain/LangGraph, CrewAI, and Cursor/Claude Desktop MCP.
• Architectural Differentiation: Added explicit comparison vs traditional RBAC/MCP proxies (Bifrost, Obot, MCPX, MintMCP).
• Security & Integrity: Security policy alignment, SPDX SBOM, and Sigstore provenance attestations on all native artifacts.
• PyPI Release: Native wheels published for Linux, macOS (x86_64 and arm64), and Windows.