docs: align READMEs with PAIDEIA and verified opencode workflow

[TaewoooPark]

Summary

Align both English and Korean READMEs with the original PAIDEIA's visual structure and 16-section order, while preserving the actual standalone CLI workflow.

• Explain the 17 commands (init aliases init-course), stage specifications and opencode run, and separate --strategy invocations for blind/twin drills.
• Correct default/selectable OCR, Markdown passthrough, vision-only PDF ingest, bootstrap/Git behavior, cross-edition migration, and artifact-derived status. Document the actual permission settings, --dry-run writes, and optional PDF export warnings. Reindex/graph are not shipped.
• Add four real CLI screenshots captured on this Mac, with commands and scope in docs/media/README.md. Recognition badges and the interactive demo are explicitly attributed to original PAIDEIA.

Validation

• Audited the CLI dispatcher, command implementations, process driver, stage/phase/workspace helpers, prompt specifications, and Python scripts against original PAIDEIA at e31672f.
• Existing Node regression suite: 113 passed.
• Real CLI on macOS with opencode 1.17.9: course initialization, Markdown ingest (three synthetic files), help, doctor, and status succeeded. Commands invoked this checkout directly rather than the older global symlink.
• Separate live analyze attempts encountered provider availability/authentication failures (including a 502 on the free model and an OpenAI refresh-token 401). Full model-generated analysis/grading and PDF vision are not claimed as verified by the Markdown-ingest screenshots. Doctor's local checks passed independently of those provider requests.
• Rendered both READMEs through GitHub's Markdown API; checked section count, local links/images, code fences, gallery markup, and git diff --check.

Documentation and screenshot assets only; runtime code is unchanged.

@TaewoooPark 검토 부탁드립니다. 기본 브랜치에 직접 푸시하지 않고 별도 브랜치에서 PR로 올립니다.