[SaladDay]

Checkpoint support is admitted for nodes and direct registrations, and the E2B Provider implements every checkpoint operation with the pinned SDK's native pause and connect.

• Adds RenewCompute as the tenth checkpoint operation (protocol, node wire, docs en/zh). Core uses it for the running phase when the Runtime is connected, since Renew addresses only the initial incarnation.
• E2B: Go adapter and Python helper for all ten operations. One sandbox spans generations; the helper receipt records the generation, pause and resume, so superseded generations are ErrNotFound and kills and snapshot deletes never touch another generation's sandbox. Wake uses the new exported runtimebootstrap.SuspendControlFile.
• Docker stays unsupported. The Web suspension copy follows the deployment mode.
• Tests: helper tests with the fake SDK, direct registration, a direct idle suspend and wake integration test with native lease renewal.

Not run: Web vitest and website translation test (no dependencies installed), real E2B, mx, full make check.

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