What does this PR do?

This PR fixes cron jobs created from gateway sessions (for example Weixin) inheriting an invalid legacy provider at execution time.
When provider or base_url is omitted on cronjob(action="create"), the tool now resolves runtime defaults from the active session and persists them into the job.

Related Issue

Fixes #13288

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

• Updated tools/cronjob_tools.py to resolve runtime defaults for cron create when provider/base_url are not explicitly passed.
• Preserved explicit provider and base_url values when users provide them.
• Kept runtime-resolution failures non-fatal to preserve existing behavior in constrained environments.
• Added regressions in tests/tools/test_cronjob_tools.py for gateway-session inheritance and explicit-override preservation.

How to Test

1. Run uv run --frozen --python 3.11 --extra dev pytest -o addopts= tests/tools/test_cronjob_tools.py -q
2. Verify new tests pass:
   • test_create_inherits_runtime_provider_when_missing
   • test_create_preserves_explicit_provider_and_base_url
3. Optionally create a cron job from a gateway session without explicit provider/base_url and confirm the stored job fields inherit runtime provider settings.

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: Windows 10 (Git Bash/PowerShell with uv-managed Python 3.11)

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

Screenshots / Logs

• uv run --frozen --python 3.11 --extra dev pytest -o addopts= tests/tools/test_cronjob_tools.py -q -> 27 passed