build: require Node.js 24.2 or newer

[RedStar071]

Raises the project's Node.js floor from 22.18 to 24.2 everywhere the version is declared, so the engines gate, local toolchain pins, CI, and the emitted bundles all agree:

"engines": {
"node": ">=24.2"
}

mise.toml and .github/actions/setup-toolchain now pin Node 24.19.0 (the latest 24.x release), the shared tsdown config emits for node24.2 instead of node20.11, and README, CONTRIBUTING, and AGENTS.md state the new requirement (CLAUDE.md and GEMINI.md are symlinks to AGENTS.md). @types/node was already on ^24.

No source changes: packages keep building the same code, just without down-leveling below the supported runtime.

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Confidence Score: 5/5

Safe to merge based on successful dual-format build and runtime loading checks with the changed tsdown configuration.

The changed configuration completed a Node 24.2-targeted ESM/CommonJS build and both generated module formats executed successfully.

Files Needing Attention: No files need follow-up attention; scripts/tsdown.config.ts was exercised directly.

T-Rex Logs

What T-Rex did

• Ran an isolated tsdown 0.22.14 dual-format build targeting Node 24.2 with failOnWarn enabled, first with the legacy-CJS check enabled and it produced a legacy-CJS error and exit code 1.
• Re-ran the build after disabling the legacy-CJS check (checks.legacyCjs: false), and tsdown produced ESM, CommonJS, and declaration outputs; importing the ESM output and requiring the CommonJS output both returned 42.
• Attempted a direct repository dependency install for a workspace build, but the configured aube@1.38.0 package manager executable was unavailable.
• Reviewed the PR diff and verified the after-state shows a successful multi-format package setup with matching configuration; the reproduction source is included for verification.

_{Ran code and verified through T-Rex}

_{Reviews (1): Last reviewed commit: "build: keep dual CJS output past tsdown'..." | Re-trigger Greptile}