Align SDK Node support with first-party consumer requirements

[betegon]

Follow-up to evaluate after the object-client DX change merges. Part of v1.0.0.

Compatibility question

The SDK declares Node >=22, while the CLI declares Node >=20.

This mismatch predates the object-client work: the CLI's existing @sentry/api 0.256.0 lockfile entry already requires Node >=22. The CLI bundles dependencies with esbuild, but a compilation target alone does not establish compatibility of runtime APIs.

The review's package smoke test passed on Node 26. It did not establish support for Node 20 or all advertised consumer versions. No runtime failure on those versions is being claimed here.

Scope and acceptance criteria

• Inventory actual SDK runtime requirements and the minimum versions promised by CLI, MCP, and external Node consumers.
• Decide the supported SDK Node floor and document the rationale. Coordinate a consumer support change if required; do not lower engines without evidence.
• Test the packed npm artifact on the chosen minimum supported Node version, covering imports, a typed operation with mocked HTTP, request/response handling, and cancellation.
• Align package metadata, consumer dependency/support declarations, and CI coverage with that decision.
• Record any distinction between direct package consumption and a consumer's bundled distribution.

Keep this focused on the runtime support decision. TypeScript module-resolution compatibility and the broader browser/Bun matrix remain part of the v1 tracking issue.