Ports everything the six lecture notebooks relied on that the initial
extraction had dropped:

- Extensive-form: plot_tree, normal-form conversion + induced analysis
  (solve_nf, pure_nash_nf, dominance, iesds_explain), info sets,
  plot_frontier/mixed/br_map, price_of_anarchy, simulate, 4 sweeps
- Stochastic: GeneralSumSG and CheapTalkGame classes; simulate,
  plot_trajectories, q_values/plot_q_heatmap, bellman_certificate,
  exploitability_analysis, gamma_sweep, perturbation_robustness, walkthrough
- Bayesian: per-mechanism explain + simulate, EntryGame, and all plots
  (revenue/bid/payments/utility-sweep/signaling/...)
- Normal-form: plot_mixed, plot_br_curves, sweeps, iesds_explain, display,
  row_name/col_name, full solve() flag set; 6 applied game factories
- Zero-sum: support enumeration + support_detail, lp_detail, security_analysis,
  plot_mixed/value_surface/security_levels/exploitability, sweep_value
- Correlated: verify_ce/cce, lp_detail, plot_payoff_region, plot_welfare_comparison

New: 6 solver _extra modules, 6 game modules (REGISTRY now 41 games),
networkx dependency. 92 tests pass, pyflakes clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>