Add new Job Search V lecture on risk-sensitive preferences

This commit adds a new lecture on risk-sensitive preferences in the job
search context, positioned after the fitted VFI lecture. The lecture
introduces entropic risk-adjusted expectations and applies them to the
McCall search model.

Changes:
- Add mccall_risk.md: New lecture on risk-sensitive preferences
- Update _toc.yml: Insert mccall_risk after mccall_fitted_vfi
- Renumber subsequent lectures (V→VI, VI→VII, VII→VIII, VIII→IX, IX→X)
  - mccall_persist_trans: V → VI
  - career: VI → VII
  - jv: VII → VIII
  - odu: VIII → IX
  - mccall_q: IX → X

Key features of the new lecture:
- Introduction to risk-sensitive preferences via entropic risk measure
- Examples with Gaussian and Beta distributions
- Mean-preserving spread analysis
- Application to McCall job search model with risk aversion
- Analysis of reservation wages and unemployment rates vs risk aversion
- All code verified to run successfully with JAX

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: jstac

lectures/_toc.yml

@@ -67,6 +67,7 @@ parts:
   - file: mccall_model_with_separation
   - file: mccall_model_with_sep_markov
   - file: mccall_fitted_vfi
+  - file: mccall_risk
   - file: mccall_persist_trans
   - file: career
   - file: jv

lectures/career.md

@@ -18,7 +18,7 @@ kernelspec:
 </div>
 ```
 
-# Job Search VI: Modeling Career Choice
+# Job Search VII: Modeling Career Choice
 
 ```{index} single: Modeling; Career Choice
 ```

lectures/jv.md

@@ -18,7 +18,7 @@ kernelspec:
 </div>
 ```
 
-# {index}`Job Search VII: On-the-Job Search <single: Job Search VII: On-the-Job Search>`
+# {index}`Job Search VIII: On-the-Job Search <single: Job Search VIII: On-the-Job Search>`
 
 ```{index} single: Models; On-the-Job Search
 ```

lectures/mccall_persist_trans.md

@@ -19,7 +19,7 @@ kernelspec:
 </div>
 ```
 
-# Job Search V: Persistent and Transitory Wage Shocks
+# Job Search VI: Persistent and Transitory Wage Shocks
 
 ```{include} _admonition/gpu.md
 ```

lectures/mccall_q.md

@@ -11,7 +11,7 @@ kernelspec:
   name: python3
 ---
 
-# Job Search IX: Search with Q-Learning
+# Job Search X: Search with Q-Learning
 
 ## Overview