Agent Skills: implement-plugin-parity

This skill should be used to execute an APPROVED plugin-parity routing artifact produced by analyze-plugin. It hard-gates on `status:"approved"`, then performs only the artifact's declared deterministic actions — emitting MCP/LSP into agent variants via the existing generators/installers, enabling vendor equivalents, and scaffolding `synced-from`-stamped Lisa skills for approved reimplement cases. It reuses Lisa's existing generators/installers as black boxes and NEVER ports upstream plugin code. An un-approved or schema-invalid artifact is a no-op error.