@workflow/world has 13 test files and no `test` script, so none of them run in CI

[pranaygp]

Noticed while adding a guard test in #3728.

packages/world/package.json defines build, dev and clean — but no test. The root test script is turbo test, which runs each package's own test script, so the 13 .test.ts files under packages/world/src/ have never run in CI.

Running them by hand:

$ npx vitest run --root packages/world
 Test Files  1 failed | 12 passed (13)
      Tests  1 failed | 152 passed (153)

The failure is real and pre-existing on main:

FAIL  src/spec-version.test.ts > spec version constants > current spec version is the compression version
AssertionError: expected 6 to be 5

  expect(SPEC_VERSION_CURRENT).toBe(SPEC_VERSION_SUPPORTS_COMPRESSION);
  expect(SPEC_VERSION_SUPPORTS_COMPRESSION).toBe(5);

SPEC_VERSION_CURRENT moved to 6 and the assertion pinning it to the compression version was never updated — exactly the kind of thing the test existed to catch, and it went unnoticed because the suite is unwired.

Fix

1. Add "test": "vitest run src" to packages/world/package.json, matching the other packages.
2. Update src/spec-version.test.ts for the current spec version — worth a moment's thought rather than just re-pinning the number, since the assertion was encoding "current == compression version" as an invariant and that is no longer true.
3. Confirm turbo test picks the package up.

Small but load-bearing: @workflow/world is the contract package every world implementation is written against, so it is a bad one to have untested.