CLI: support worker-based execution

[atravitz]

LLM / AI generated code disclosure

LLMs or other AI-powered tools (beyond simple IDE use cases) were used in this contribution: no

Checklist

• All new code is appropriately documented (user-facing code must have complete docstrings).
• Added a news entry, or the changes are not user-facing.
• Ran pre-commit: you can run pre-commit locally or comment on this PR with pre-commit.ci autofix.
• Filled in the AI generated code disclosure.

Manual Tests: these are slow so don't need to be run every commit, only before merging and when relevant changes are made (generally at reviewer-discretion).

• GPU integration tests
• example notebook testing
• packaging tests: run this for any large feature PRs or PRs that add test data.

Developers certificate of origin

• I certify that this contribution is covered by the MIT License here and the Developer Certificate of Origin at https://developercertificate.org/.

[codecov]

Codecov Report

❌ Patch coverage is 97.63780% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.59%. Comparing base (c4137e6) to head (13fee8b).

Files with missing lines	Patch %	Lines
src/openfecli/commands/run_worker.py	83.33%	2 Missing ⚠️
src/openfecli/commands/plan_rhfe_network.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@                       Coverage Diff                       @@
##           epic/execution_improvements    #2174      +/-   ##
===============================================================
+ Coverage                        90.56%   90.59%   +0.03%     
===============================================================
  Files                              219      224       +5     
  Lines                            21449    21539      +90     
===============================================================
+ Hits                             19425    19513      +88     
- Misses                            2024     2026       +2     

Flag	Coverage Δ
fast-tests	90.59% <97.63%> (+0.03%)	⬆️

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