Add simulator replica, persistence, planet scan, README; split empire state out of the repo

- tools/simulate.py + puga/simulate.py: replica of PRUNplanner's simulator (flows and
  efficiency verified against screenshots), reports real new capex (planned minus built)
- tools/scan.py: staffing variants, freight, HQ/experts, --planet mode, demolish-later,
  --min-n as a pure market-size filter, --json output
- tools/history.py, tools/persistence.py: margin history and short-horizon payback checks
- tools/plan_push.py: guarded delete; tools/state.py: syncs to empire/
- README with features and setup; CLAUDE.md made generic
- Own-empire material (profile, state, plans, notes) moved to gitignored empire/;
  generic examples in plans/examples and state/company.example.yaml

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -4,3 +4,5 @@ data/cache/
 ref/
 __pycache__/
 .pytest_cache/
+empire/
+data/