Changelog catchup

[phinze]

Mid-cycle changelog update: fills in the Unreleased section with everything merged since v0.10.0.

Two features (version retention GC, absolute time-window filtering for miren logs), a handful of build/deploy/operational improvements, and a batch of reliability bug fixes. Distributed-runner and saga work is excluded since it's still behind Miren Labs flags, along with docs-infra and test-only changes.

Wording got a voice pass against the brand guide: user-centric framing, problem-first, and toned down from incident-report drama to honest-but-calm.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: a7d6100c-7ef1-463b-8f93-b722d24bd470

📥 Commits

Reviewing files that changed from the base of the PR and between b088fb9 and 72e057d.

📒 Files selected for processing (1)

• docs/docs/changelog.md

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📝 Walkthrough

Walkthrough

This change updates the documentation-only changelog file to populate the previously empty "Unreleased" section with entries organized under Features, Improvements, Bug Fixes, and Documentation headings. The entries describe items such as version retention, log time-window flags, deploy health behavior, various reliability fixes, and documentation updates including removal of a reference to post_import. No code or public API changes are included.

Changes

Cohort / File(s)	Change Summary
docs/docs/changelog.md	Added Unreleased section entries under Features, Improvements, Bug Fixes, and Documentation headings

Sequence Diagram(s)

No sequence diagram generated, as this is a documentation-only change with no code behavior, API, or control flow modifications.

Estimated code review effort: 1 (Low)

Related issues: None provided.

Related PRs: None provided.

Suggested labels: documentation

Suggested reviewers: None identified from provided context.

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🐰 A whisper of changes, penned in the night,
Bullet points blooming, changelog grown bright,
Fixes and features, all lined in a row,
No code was disturbed, just words that now flow.

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