Add Node.js validation and test gates

[dahlia]

Problem

Almost every maintained test already uses node:test, but the suite is executed by Deno and still relies on Deno environment, file-system, server, and test helpers. Node.js cannot become the production runtime until the same code is validated there continuously.

Tasks

• Add Node.js type-check, lint, format, code-generation, and test commands behind mise.
• Choose and document the TypeScript execution strategy for tests and scripts.
• Replace the remaining Deno.test declaration.
• Remove or transform TypeScript syntax that Node's strip-only mode cannot execute, or use a consistent build/test transformer.
• Port environment locking, temporary-directory, local HTTP-server, and database test helpers.
• Run pure unit tests first, then DB, GraphQL, federation, and web-next tests.
• Add Node.js gates to CI while keeping Deno gates during the transition.

Acceptance criteria

• All maintained non-legacy tests pass under Node.js.
• Type checking and generated-artifact checks run without Deno.
• CI blocks regressions in the Node.js path.
• Test isolation and parallel database behavior remain equivalent to the current suite.

AI assistance: This issue was drafted and organized with Codex after a maintainer-led code audit.