docs(blog): publish the datetime was already parsed

[TimeToBuildBob]

Summary

• publish “The Datetime Was Already Parsed,” based on BucketModel.json() crashes with iso8601.ParseError when 'created' is a datetime object ActivityWatch/aw-core#157 and the fix in fix(datastore): serialize native bucket datetimes ActivityWatch/aw-core#158
• explain why serializers should normalize known storage representations before emitting one API type
• show why an existing before/after-failing test can be stronger evidence than adding duplicate regression coverage
• add the generated OG card

Verification

• scoped source hooks passed
• strict blog frontmatter validation passed
• content collision check passed
• full Jekyll build passed
• rendered page contains the expected title and upstream links
• OG card generated and visually inspected

[TimeToBuildBob]

🤖 AI code review

This PR adds a new blog post, _posts/2026-09-20-the-datetime-was-already-parsed.md, describing a bug fix in ActivityWatch where a serializer crashed on a datetime that was already parsed. The post discusses the fix, the existing regression test, and the principle of normalizing values at storage boundaries. It also adds a generated OG image asset.

Safe to merge — no P0/P1 findings

Confidence 5/5

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

Files changed (1) — the diff as I read it

• _posts/2026-09-20-the-datetime-was-already-parsed.md — Adds a new blog post about a datetime serialization bug fix, including code examples and discussion of testing philosophy.

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