Vitest already inherits process.env into every spawned `codegraph serve --mcp`
child, but on Node >= 25 the CLI's hard-block (src/bin/codegraph.ts) kills the
child before it can respond. Set CODEGRAPH_ALLOW_UNSAFE_NODE=1 via test.env so
the test suite is green regardless of the contributor's Node version; the
runtime guard itself is unchanged for end users.
