V0.16.3: PyPI summary + keyword refresh naming etch-verify

Metadata-only patch bump. No code changes. Every code path shipped in v0.16.2 continues to work identically. Rewrite PyPI summary from "MCP server that builds a world model for codebases to prevent hallucinations, repeated mistakes, and regressions" to "MCP world-model memory server for coding agents; ships the etch-verify offline audit-chain verifier CLI". The etch-verify offline audit-chain verifier CLI is a first-class entry point in [project.scripts] and has been installed by every prior release;