YAML verification: { type: exit_code } with no value fails a passing step (compares "0" vs undefined)

[khaliqgant]

Summary

In a YAML workflow, an agent step with verification: { type: exit_code } and
no value fails a step that actually succeeded, with:

Verification failed for "draft": recorded exit code "0" did not match "undefined"

The agent exited 0 (success), but because no expected value was supplied the
engine compares "0" against undefined and fails. The natural author intent —
"pass if the step exits 0" — is silently wrong.

Repro

- name: draft
  type: agent
  agent: drafter
  task: |
    ...write out/draft.md...
  verification:
    type: exit_code        # no `value:` -> compares "0" vs undefined -> FAIL

Run → the step runs fine, produces its artifact, exits 0, and the workflow still
reports FAILED at that step.

Fix on the author side: add value: '0'.

Notes

• The bundled example examples/yaml/fix-dashboard-user-registration.yaml uses
  the same verification: { type: exit_code } (no value) on its agent steps, so
  it presumably hits this too.
• The TS builder examples write { type: 'exit_code', value: '0' }; the YAML
  path should behave the same when value is omitted.

Expected

verification: { type: exit_code } with no value should default to '0'
(success), OR flows/relayflows validation (--dry-run) should reject the
step up front with a clear "exit_code verification requires a value" error —
never silently fail a passing step at runtime.

Acceptance criteria

• type: exit_code with no value either defaults to '0' or fails validation
  at --dry-run, with a message naming the fix.
• The bundled YAML example is updated accordingly.

Context

Hit while preparing a first-run example for a prospect (Altek). relayflows CLI 1.0.6.