fix: non-zero exit code when a workflow run ends failed or aborted

[doquanghuy]

Description

Fixes #2958.

workflow run and workflow resume ended with exit code 0 even when the run finished Status: failed, so scripts/CI had to parse stdout to detect failure. This PR adds a single status→exit-code mapping (_run_outcome_exit_code: failed/aborted → 1; completed/paused → 0 — paused is a waiting state, not a failure) and applies it at the four epilogues (run/resume × text/--json). The --json payload itself is unchanged — it still prints first; only the process exit code changes.

Behavior change, flagged plainly: the old behavior was deliberately pinned by tests/test_workflow_run_without_project.py::test_workflow_run_failing_yaml_without_project (exit_code == 0 asserted on a failed run). That pin is updated to the new contract with an explanatory comment. Anyone scripting against exit-0-on-failed would be affected — the issue discusses the trade-off; happy to gate this behind a flag instead if you'd rather not change the default.

Testing

• Ran existing tests with uv sync && uv run pytest — full suite 3728 passed
• New TestWorkflowRunExitCodes (3 CLI-level tests): failed→1 (text + --json), completed→0; the two failure-path tests are red against current main, green with the fix (verified both directions)
• uvx ruff check src/ — clean
• Tested locally with uv run specify --help
• Tested with a sample project (covered by the CLI-level tests, which drive real workflow YAML files end-to-end through CliRunner)

AI Disclosure

• I did not use AI assistance for this contribution
• I did use AI assistance (describe below)

Code, tests, and this description were authored with AI assistance (Claude); verified by running the repo's test suite and ruff locally in both red (unfixed) and green (fixed) directions.

[doquanghuy]

@mnriem when you have a moment, would appreciate a review — happy to adjust anything.