[Docs] Align public docs with recent product changes

[roomote-community]

​Created by Roomote. View the task or mention @roomote for follow-up asks.

What changed

• Document automation run-history links and the structured metadata shown in Slack automation reports.
• Add the environment editor's Diff view to the environment overview and definition reference.
• Clarify resumable Brain backfills and the Brain-first lookup order agents use before overlapping live sources.

Why this change was made

Recent user-facing changes on develop added these workflows and behaviors without complete corresponding public guidance. This update aligns the documentation with the shipped product while leaving internal-only changes out of the public docs.

Impact

Users and operators can now find accurate guidance for reviewing previous automation runs, understanding Slack automation reports, comparing environment drafts, and knowing how Brain ingestion and retrieval behave.

Screenshots

[roomote-community]

No code issues found. See task

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