ErrorBoundary: chunk load failures need a stable signal and consistent routing

Since #8998, a component whose chunk fails to import no longer loops, and the nearest <ErrorBoundary> renders its fallback. I think that is the right default, but two things are missing.

Apps cannot reliably detect a chunk load failure

The error that reaches onError$ is the browser's TypeError and the phase is render. The message differs per browser:

• Chrome: Failed to fetch dynamically imported module
• Firefox: error loading dynamically imported module
• Safari: Importing a module script failed

The usual fix for a chunk 404 after a deploy is location.reload(), and onError$ has no stable way to tell "code is missing" from "code threw". Options:

• add an ErrorBoundaryPhase.Import value
• or tag the error in the .catch added by #8998 in executeComponentChore (packages/qwik/src/core/shared/cursor/chore-execution.ts)

Event handler chunk failures are not routed to boundaries

When an onClick$ chunk fails to import, the qwikloader emits qerror with importError set, and handleQError returns early (packages/qwik/src/core/shared/error/error-handling.ts). The error only reaches console.error. There is a test for this.

So today a broken component chunk shows the fallback, while a broken handler chunk shows nothing. Both are the same situation for the user. If we add an import phase, the qwikloader case should go through it too.

Verified

Spec run on current main:

Read packages/qwik/src/core/shared/cursor/chore-execution.ts at the catch added by #8998 and packages/qwik/src/core/shared/error/error-handling.ts at handleQError, then inspect the existing test for qwikloader import failures. Define a stable import-failure signal and route component and event-handler chunk failures consistently through ErrorBoundary handling, with tests covering both paths.