test(machine): rewrite State.spec.ts — drop smoke tests, strengthen withOverrodeHaltState

[mellonis]

Task 7/10. Two audit categories: drop smoke tests, strengthen `withOverrodeHaltState`.

Smoke tests dropped

• `'State'` — `expect(new State()).toBeTruthy()`.
• `'has id'` — `expect(...).toBeDefined()`.
• `'getSymbol exists'`, `'getCommand exists'`, `'getNextState exists'` — all `toBeTruthy` smoke checks.
• Several redundant `expect(state).toBeTruthy()` lines next to behavior assertions in the constructor happy-path tests.

Method existence is already asserted by every test that calls these methods or constructs a State — these were nominal checks that didn't add coverage.

withOverrodeHaltState strengthening

Audit caught: the previous test only asserted the wrapper's name pattern. Five focused tests now pin the actual contract:

• Wrapper exposes the override target on `.overrodeHaltState`; original is unchanged.
• Wrapper proxies `getCommand` and `getNextState` to the original's symbol-to-data map.
• Wrapper shares `debugRef` with the original (v4 ref-share contract — assignment on either visible from both).
• Wrapper has its own `id` distinct from the original.
• Wrapper name encodes the override target ("${original.name}>${override.name}").

Numbers

• Test count: 21 → 18 (net -3, but coverage of the actual contract is significantly stronger).
• Total: 381 tests pass.
• Coverage: unchanged.