[Roadmap] Update and add tutorials (turnpike, AD, free times, state constraints, etc.)

## Objective

Update existing tutorials and add new ones. Improve "tricks and tips" style tutorials.

## Scope

New tutorials to add:
- Turnpike
- Automatic differentiation (AD)
- Free final time
- State constraints
- Impulsional cases
- Abnormal cases
- Good initial guess
- ML and optimal control

Also update existing tutorials for OptimalControl v2 compatibility.

## Why

Tutorials are the primary entry point for new users. Keeping them up to date and covering diverse topics makes the ecosystem more accessible and demonstrates its capabilities.

## References

- [Tutorials.jl](https://github.com/control-toolbox/Tutorials.jl)
- [Roadmap comment](https://github.com/orgs/control-toolbox/discussions/68#discussioncomment-17584843)