core: pending question forms cancelled by a location close get no cause or question content #52599

Description

When a location is evicted after 60 idle minutes, its pending question forms are cancelled when the location closes, with a bare { status: "cancelled" } — no reason, no content. The client that rendered the form sees the question cancel silently: the state does not say that the location was evicted, or which question was pending. In the tool failure reported back to the model, a close-caused cancel says only "Interaction cancelled because the location shut down" (#51647's symptom) — again without the pending question content.

The close path has no way to record why it is cancelling: Form.close cancels every pending form with no options, and the cancelled state has nowhere to carry a cause or the pending question content.

This issue is about the cancellation state and message, not the eviction policy — the policy is discussed in #51343, and restoring pending forms across reconnects is a separate issue (#44471).

OpenCode version

2.0.8

Steps to reproduce

1. Start a session, get a question form pending, and let the session go idle (no active execution) until its location hits the 60-minute idle deadline.
2. The location is evicted and the close cancels the pending form.
3. Observe: the form's state is { status: "cancelled" } — no reason, no pending question content.

Expected: the cancelled state should include why it was cancelled (for eviction, cause: "evicted") and enough context to identify the pending question.