fix(core): dispose internal/update hooks with the fiber

[tdwhere123]

Problem

Non-global ctx.on('internal/update') is intercepted in EventsService and stored on fiber._hooks, then on() returns early so the listener never becomes a fiber effect. _unload only clears _disposables. The Fiber instance is reused across reloads, so each fiber.update() keeps the previous generation's closures.

Three config updates on current main therefore dispatch 1 + 2 + 3 listeners:

Observation	Current main	This change
update({ n: 1/2/3 })	[1, 2, 2, 3, 3, 3]	[1, 2, 3]
explicit dispose() before update	that generation does not run	unchanged
{ global: true } listener	not tied to child reload	unchanged

The accumulation regressions fail on 8cc9e33 with those extra calls and pass on this branch.

Change

Register the special-cased listener through fiber.effect, so _unload already drops it. Do not clear fiber._hooks and do not touch _unload (that path is being rewritten in #39).

This PR is independent of #55 (internal/status isolation) and does not change register() / _resolve (#51).

Regression coverage

packages/core/tests/update-hooks.spec.ts covers accumulation across reloads, explicit dispose of the current generation, and that global internal/update hooks are not bound to a child fiber's reload.

Validation

• yarn lint
• yarn yakumo tsc
• yarn test cordis/update-hooks — 3 tests passed
• yarn test cordis — 13 files, 74 tests passed
• yarn test:json — 20 files, 166 tests passed
• git diff --check origin/main...HEAD — passed