feat(core): report inconclusive status when all tests have execution errors

[christso]

Summary

When all eval tests fail due to execution errors (e.g., misconfigured model, network failures, auth errors), the run now reports a distinct INCONCLUSIVE status instead of a misleading PASS/FAIL verdict.

• Exit code 2 for all-execution-error runs (distinct from exit 1 for threshold failures), so CI workflows can differentiate
• Yellow INCONCLUSIVE verdict in CLI output: RESULT: INCONCLUSIVE (all N test(s) had execution errors — no evaluation was performed)
• JUnit XML uses executionStatus to classify <error> vs <failure> elements, preventing execution errors from being double-counted as failures

Test plan

• New unit tests for INCONCLUSIVE verdict formatting (statistics-inconclusive.test.ts)
• New unit tests for JUnit error/failure classification by executionStatus
• Existing tests updated and passing
• Typecheck passes
• Lint passes
• Manual red/green UAT with a misconfigured model target

Closes #894

🤖 Generated with Claude Code

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View logs

[christso]

Manual Red/Green UAT

Scenario: Run eval with a nonexistent Azure deployment (AZURE_DEPLOYMENT_NAME=nonexistent-model-xyz-404) so all tests produce execution errors.

Red (main) — misleading PASS with exit code 0

2/2   ❌ test-1 | azure | ERROR: The API deployment for this resource does not exist...
2/2   ❌ test-2 | azure | ERROR: The API deployment for this resource does not exist...

RESULT: PASS  (0/0 scored >= 0.8, mean: 0.000)

EXIT CODE: 0

All tests errored, but the run reports PASS with exit code 0 — CI would treat this as success.

Green (this branch) — clear INCONCLUSIVE with exit code 2

2/2   ❌ test-1 | azure | ERROR: The API deployment for this resource does not exist...
2/2   ❌ test-2 | azure | ERROR: The API deployment for this resource does not exist...

RESULT: INCONCLUSIVE  (all 2 test(s) had execution errors — no evaluation was performed)

EXIT CODE: 2

Now reports INCONCLUSIVE with distinct exit code 2, so CI can differentiate between threshold failure (exit 1), execution errors (exit 2), and success (exit 0).