fix(cli): report terminal outcomes for noninteractive runs - #60508

Problem

opencode run --format=json can exit 1 and emit an error even when an interrupted model response recovers and the execution succeeds. Scripts and CI consumers cannot distinguish a recovered step from a failed run.

Fixes #50062.

Change

 failed model step
-  emit fatal JSON error and set exit 1
+  allow execution to continue
 execution becomes idle
-  treat any historical assistant error as fatal
+  use the terminal execution event or projected idle marker

Keep V1 behavior, real execution failures, SIGINT, and local cancellation exit codes. Wait for the terminal event when the idle marker has not projected yet, even if an assistant already responded. Non-question forms still fail non-interactive runs, now with an explicit diagnostic; question cancellation remains recoverable.

Related: #52885 addresses exit status. This also removes recovered-step JSON errors and uses execution markers, not the last assistant, when terminal events lag or are missing.

Out of scope

No model retry policy, Core/API changes, or new JSON event types. Step usage reconciliation is unchanged.

Verification

• bun test test/run --timeout 30000 --rerun-each 10 --only-failures: 240 pass.
• Full CLI bun test --timeout 30000 --only-failures: 364 pass, 9 skip, 0 fail across 54 files.
• CLI bun typecheck: pass.
• CLI bun run typecheck:tsc: pass.
• Root bun run check: pass with existing lint warnings.
• Regression coverage includes live/projected recovery, terminal failures after a clean assistant, delayed/missing terminal events, stream disconnection, interruption, form cancellation, and V1 behavior.

Visual

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Added by the opencode bot (AI-generated).

Related: #39573

Public API: opencode run: no error event or exit 1 for recovered steps; adds an explanatory error for cancelled non-question forms (event types unchanged, backwards compatible)