fix(cron): skip whitespace-only job responses

[joe102084]

Summary

• Treat whitespace-only cron final responses like empty responses so scheduled jobs do not attempt to deliver blank messages.
• Keep the existing soft-failure guard semantics: successful runs with blank/whitespace final responses are marked as non-ok instead of silently passing.
• Add regression coverage for whitespace-only cron output.

Spec / Behavior

• Given a successful cron job result with final_response containing only spaces/newlines, delivery should be skipped.
• The run should still be marked with the existing empty-response soft failure path so operators can diagnose provider/model issues.
• Non-empty responses and explicit [SILENT] behavior remain unchanged.

Test Plan

• scripts/run_tests.sh tests/cron/test_scheduler.py -q
• git diff --check main...HEAD

Notes

• This PR intentionally avoids unrelated local working-tree changes.

[alt-glitch]

Duplicate of merged #28352 — identical fix adding .strip() to bool(deliver_content) and final_response empty check in _process_job(). #28352 was merged on 2026-05-19.

[teknium1]

Automated hermes-sweeper review: this looks implemented on current main via the already-merged duplicate PR #28352.

Evidence:

• PR fix(cron): handle whitespace-only responses (#28151) #28352 (fix(cron): handle whitespace-only responses (#28151)) was merged on 2026-05-19 as 6143013f5bb7a1e2a761a59997a0bca07c05bfe1.
• cron/scheduler.py:2062 now uses bool(deliver_content.strip()), so whitespace-only cron responses do not deliver blank messages.
• cron/scheduler.py:2078 now uses not final_response.strip() for the empty-response soft-failure path, preserving the diagnostic behavior requested here.
• tests/cron/test_scheduler.py:1955 includes regression coverage for whitespace-only responses being marked failed and not delivered.

Thanks for the fix; the same change has already landed on main.