build(release): prepare 8.0.0

Merge pull request #10 from skill-mill/feat/min-age

feat(update): add min-age git history resolution

fix(cli): align sync provenance behavior

feat(cli): unify project directory resolution

feat(sync): use project directories by default

fix(codex): prevent openai.yaml leakage on direct sync

build: reorganize pnpm scripts

build: migrate package manager to pnpm

docs: add README FAQ, unreleased CHANGELOG entries

docs: restructure README and move advanced sections to docs/

7.0.1

docs: rename download to add in documentation and help text

feat!: rename CLI to sk, directories to .agent-skill-porter

docs: restructure README and move advanced sections to docs/