Convert wealth dynamics lecture from NumPy/Numba to JAX

[Copilot]

This PR converts the wealth dynamics lecture to use JAX instead of NumPy/Numba, addressing issue #812b7e3e-c818-4a29-a183-7a25078f0a8d.

Changes Made

JAX Conversion:

• Replaced NumPy/Numba imports with JAX equivalents (jax, jax.numpy as jnp, typing.NamedTuple)
• Converted the @jitclass WealthDynamics class to a JAX-compatible NamedTuple pattern
• Updated all random number generation to use JAX's functional PRNG with proper key management
• Applied @jax.jit decorators to performance-critical functions for optimization
• Replaced NumPy array operations with JAX equivalents (jnp.exp, jnp.sqrt, etc.)
• Implemented JAX-style control flow using jnp.where and jax.lax.scan

Technical Improvements:

• Added 64-bit precision configuration with jax.config.update("jax_enable_x64", True)
• Fixed QuantEcon function calls to work with JAX arrays by converting with np.array()
• Implemented vectorized operations using jax.vmap for efficient parallel computation
• Used memory-efficient jax.lax.scan instead of Python loops for time series generation

Code Quality:

• Applied QuantEcon style guide formatting with consistent indentation and structure
• Fixed spelling errors and improved grammar throughout
• Cleaned up trailing whitespace and formatting inconsistencies
• Updated plot labels for clarity and consistency
• Added comprehensive docstrings following established patterns

Verification:

• All core model functions tested and working correctly
• Security vulnerability scan passed (0 issues found)
• Jupyter Book integration confirmed working
• JIT compilation performance validated

The lecture now uses modern JAX best practices while maintaining all original functionality and educational content. Performance is improved through JIT compilation, and the code follows functional programming patterns appropriate for scientific computing.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[wealth_dynamics] Update lecture</issue_title>
<issue_description>Please update the wealth dynamics lecture to:

1. convert all code to JAX
2. apple the QuantEcon style guide https://manual.quantecon.org/intro.html
3. check spelling
4. check grammar</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #629

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📚 Changed Lecture Pages: wealth_dynamics