[SaladDay]

Fixes the blind-review findings on the Runtime-side cleanup.

• Idle default: the column default is the one authored definition (migration 000008 restores DEFAULT 300); DefaultIdleSeconds is deleted. A setup preview carries no idle value; only the stored row does.
• Claude pin: the retained-history gate compares the SDK version with the declaration. The native Claude Code version is fixed by the SDK pin, so its literals are removed from the Go check, both scripts and the README; the README SDK pin joins NATIVE_PROJECTIONS.
• Capability mirror: runtimedevice.KindCapabilities and SupportedAgentKind, the heartbeat copy and the drift test are deleted; Core uses proto.AgentKindCapabilities and proto.SupportedAgentKind. The persisted JSON keeps the same keys.
• Admin API text is Provider-neutral; core.openapi.yaml regenerated.
• One constant each for the Harness env names and Installation.AgentKind.
• Dead bridge leftovers (Type: "start", Input) deleted.
• Added the later-function case to executor.test.mjs.
• E2B README command and sentence fixed.
• CLAUDE_CODE_GIT_BASH_PATH: nothing restored. It was a Claude variable read by the generic Windows setup shell lookup; Claude reads it natively, and setup finds Bash through git.exe.

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