fix(cron): deliver max-iteration fallback reports

[helix4u]

What does this PR do?

Fixes the cron-specific path where an agent reaches the iteration limit, produces a usable max-iteration fallback report, and then cron raises that report text as a runtime error because the generic agent result has completed=False.

The generic agent/finalizer semantics stay unchanged: max-iteration turns are still incomplete for interactive and worker paths. Cron now treats a non-empty max_iterations_reached(...) fallback response as deliverable output instead of turning the response into RuntimeError(<full report>).

This matches the support log shape from the thread: Turn ended: reason=max_iterations_reached(60/60) ... last_msg_role=assistant response_len=1707, immediately followed by cron raising the full generated price-check report.

Related Issue

Discord support thread: https://discord.com/channels/1053877538025386074/1518634271122784427

Related but separate PRs:

• fix(agent, cron): handle final reports at iteration limits #50967 covers last-call text_response(...) boundary behavior, but this thread's fresh log shows max_iterations_reached(60/60).
• Fix/discord slash sync #50890 covers the separate Discord slash-command cap error later in the same attached log.

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

• cron/scheduler.py: allow cron to deliver a non-empty max_iterations_reached(...) fallback response instead of raising it as an error when completed=False.
• tests/cron/test_scheduler.py: add regression coverage for the fresh support-log shape.

How to Test

1. Run the focused scheduler suite:
   scripts/run_tests.sh -j 4 tests/cron/test_scheduler.py
2. Confirm max-iteration fallback summaries return success=True and include the report in cron output.
3. Confirm real agent failure paths with failed=True, empty incomplete output, or explicit errors still fail.

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits (fix(scope):, feat(scope):, etc.)
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix/feature (no unrelated commits)
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes (required for bug fixes, strongly encouraged for features)
• I've tested on my platform: WSL/Linux

Documentation & Housekeeping

• I've updated relevant documentation (README, docs/, docstrings) — or N/A
• I've updated cli-config.yaml.example if I added/changed config keys — or N/A
• I've updated CONTRIBUTING.md or AGENTS.md if I changed architecture or workflows — or N/A
• I've considered cross-platform impact (Windows, macOS) per the compatibility guide — or N/A
• I've updated tool descriptions/schemas if I changed tool behavior — or N/A

For New Skills

N/A

Screenshots / Logs

Focused test run:

scripts/run_tests.sh -j 4 tests/cron/test_scheduler.py

Result: 163 tests passed.

[helix4u]

Closing as superseded by #50967. The cron fallback-summary fix from this PR has been moved onto #50967 so the support thread has one review target.