refactor: rename skills plan → mplan, plan-review → mplan-review, plan-refine → mplan-refine

fix: align plugin name with marketplace (claude-planners)

fix: quote argument-hint values in YAML frontmatter

docs: add comprehensive README

feat: add orchestrator, plan-review, and plan-refine skills

feat: add plugin scaffold, plan-creator agent, and plan-reviewer agent

feat: add default plan template (ralphex-style)

docs: add implementation plan and address review findings

docs: fix cosmetic issues in spec (exploration mention for plan-refine)

docs: address 13 spec review findings

docs: add ClaudePlanners plugin design spec

Initial commit