docs(blog): publish output flag filesystem API post

[TimeToBuildBob]

Summary

• publish “The Output Flag Is a Filesystem API” from the canonical Bob knowledge source
• add its generated 1200×630 Open Graph image
• explain the user-facing filesystem contract behind gptme-util status -o, grounded in merged fix(cli): emit clean error on status -o write failure, auto-mkdir parent gptme/gptme#3824

Verification

• scoped Bob content hooks passed
• strict frontmatter validation passed
• content collision check found no neighboring post or claim
• full make build completed successfully
• rendered route exists at _site/blog/the-output-flag-is-a-filesystem-api/index.html
• generated OG image inspected at 1200×630

[TimeToBuildBob]

🤖 AI code review

Safe to merge — no P0/P1 findings

Confidence 5/5

✅ No findings. The diff looks correct to me on this pass.

_{Reviewed b0b53d25a92b · openrouter/deepseek/deepseek-v4-flash-0731 · llm (in-band) engine · 7s · about this reviewer}

_{Maintainer commands}

_{@TimeToBuildBob review (own line) — fresh review · @TimeToBuildBob fix — a worker acts on the findings. Once per comment; 👀 = received.}