[codex] Honor explicit economy dataset selection

[MaxGhenis]

What changed

• Economy scoring now resolves explicit dataset aliases like enhanced_cps, cps, and enhanced_frs before falling back to the regional default dataset.
• Added regression tests for explicit dataset aliases in _setup_data() and at the SimulationOptions layer.
• Added repo-native make targets for fresh worktrees and PR preflight (bootstrap-dev, lint, check-changelog, pre-pr, ci).
• Updated the PR workflow to call those shared commands instead of duplicating shell logic.
• Documented the expected local workflow in README.md and CLAUDE.md so fresh sessions default to uv/make rather than ad hoc .venv/bin/... commands.

Why

The economy API accepted a dataset query param from the web app, but _setup_data() ignored most named datasets and silently used get_default_dataset(...) instead. That meant the UI could present a non-default dataset selection while the backend still scored the default dataset.

Separately, the initial PR follow-up hit avoidable worktree drift because local commands depended on implicit tool paths instead of repo-native commands. This PR now encodes the intended workflow directly in the repo and CI.

Impact

• Explicit dataset selections in society-wide calculations now reach the simulation API correctly.
• Existing default behavior and the special national-with-breakdowns passthrough datasets are unchanged.
• Fresh worktrees can use make bootstrap-dev and make pre-pr without assuming a specific shell-local tool path layout.

Validation

• make pre-pr
• make test-env-vars in a configured environment

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.24%. Comparing base (2f4cf80) to head (1e62bb1).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3380      +/-   ##
==========================================
+ Coverage   72.20%   72.24%   +0.03%     
==========================================
  Files          56       56              
  Lines        2425     2428       +3     
  Branches      423      424       +1     
==========================================
+ Hits         1751     1754       +3     
  Misses        595      595              
  Partials       79       79              

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