Add ACADOS cycling MHE support

[mickaelbegon]

Summary

• add ACADOS build/install guidance and a setup helper for conda environments
• add a torque-driven cycling moving-horizon example that solves through ACADOS
• make the FES pulse-width ACADOS limitation explicit because bioptim 3.4 does not export its numerical time series as ACADOS parameters

Note

• Recreated from Add ACADOS cycling MHE support mickaelbegon/cocofest-pedalage#2 against pyomeca/cocofest:main.
• This branch includes the bioptim 3.4 migration commits because all recreated PRs target main.

Validation

• python3 -m py_compile run_endurance_weighted_mhe.py examples/fes_multibody/cycling/cycling_pulse_width_mhe.py examples/fes_multibody/cycling/cycling_mhe_acados.py
• git diff --check
• built local ACADOS in /Users/mickaelbegon/Documents/bioptim/external/acados
• installed acados_template editable into conda env cocofest-bayes
• downloaded t_renderer through acados_template
• ran cycling_mhe_acados.main(codegen_dir="/private/tmp/cycling_mhe_acados_codegen") with ACADOS_SOURCE_DIR and DYLD_LIBRARY_PATH set

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This change is 

[mickaelbegon]

I rebuilt this branch on top of the cleaned bioptim 3.4 migration PR so the diff is now limited to the ACADOS setup + compact cycling MHE examples.

Current scope:

• docs/acados_environment.md
• scripts/setup_acados_for_conda_env.sh
• examples/fes_multibody/cycling/cycling_mhe_acados.py
• examples/fes_multibody/cycling/cycling_mhe_solver_comparison.py

I also removed the CLI parser from the comparison script to stay aligned with the feedback style already raised on PR #27.

Validation on my side:

• python -m py_compile on both ACADOS example files
• ACADOS/IPOPT comparison smoke run completed locally on a short window