[Bug]: DSH plugin continuation admission failures are not surfaced in GoalBar #8506

Reproduction

1. Enable automatic continuation for a bound Goal in the DSH plugin.
2. Have the LoopX admission call fail, for example because the heartbeat response does not pass the Driver's schema or identity check.
3. Observe the conversation and GoalBar after the current Turn ends.

Expected

GoalBar should expose that automatic continuation could not be admitted, with a safe error category and a useful recovery action. It should distinguish this failure from an idle, paused, or completed Goal without disclosing command output or private runtime paths.

Actual

The Driver writes a warning and returns from evaluation without queuing a continuation. The failure is not projected into GoalBar, so the user can see continuation stop without an explanation in the conversation UI.

Code pointers

• packages/dsh-loopx-plugin/src/driver.ts: evaluate catches admission failures, calls warn with LoopX admission failed, and returns without an error projection.
• packages/dsh-loopx-plugin/src/driver.ts: apply connects the Driver's warn callback only to ctx.logger.warn.
• packages/dsh-loopx-plugin/src/goalbar/service.ts and src/goalbar/protocol.ts: existing GoalBar read/action projection and fault vocabulary; possible owners for a bounded, public-safe failure state.

The Windows heartbeat parsing fix is separate. This issue requests user-visible admission diagnostics, not a relaxation of admission validation or automatic retries for every failure.

Related: #8504 fixes the parsing defect that exposed this; the missing diagnostics are independent of it.