docs: runner states defined beside the actions + Aug 19 changelog

[indykish]

The runner page's state chip now links a States section that defines every admin state (active, cordoned, draining, drained, revoked) and liveness value (registered, online, busy, offline) where they are shown, split by who controls each — the operator sets admin state, the host reports liveness.

The Aug 19 changelog entry covers agentsfleet M169: the sandbox scratch write-floor fix that unblocks credentialed work on hardened runners, the new scratch check in Run checks, and the runner detail page polish (Filter/Apply, icons, disabled Cordon/Drain, refresh, Time/Duration columns, the states learn-more link).

Pairs with agentsfleet feat/m169-runner-detail-polish.

🤖 Generated with Claude Code

Greptile Summary

The PR documents runner admin states and liveness values beside the runner controls and adds the Aug 19 release notes.

• Clarifies that draining automatically transitions to drained after the final lease ends.
• Defines all displayed admin-state and liveness values.
• Records the hardened-runner scratch fix, new run check, and runner-detail UI updates.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
runners.mdx	Adds runner-state definitions and resolves the previously contradictory description of the drain transition.
changelog.mdx	Adds the Aug 19 release entry covering sandbox scratch handling, run checks, and runner-page improvements.

_{Reviews (2): Last reviewed commit: "docs: name the one admin state transitio..." | Re-trigger Greptile}

Context used:

• Knowledge Base — Onboarding: landing page, quickstart, changelog, and memory