Generate a PVA operator

Implement the approved Spec contract. Do not redefine it.

Resolve paths

SKILL_ROOT is the absolute directory containing this skill's SKILL.md, after resolving symlinks. Bundled files are relative to that directory. Resolve supplied relative paths against the invocation directory before changing directories. Set OPGEN_INPUTS to the absolute handoff path and WORK_DIR to the caller's report work directory. For a handoff at <work-directory>/configure/opgen-inputs.json, default WORK_DIR to that <work-directory>; otherwise require an explicit report work directory. Use only the validated handoff's workspace as the project root.