[WAVE 2][RTR] Validate parameter interpolation types

[mickaelbegon]

Summary

• require InterpolationType.CONSTANT for parameter bounds
• apply the same validation to parameter initial guesses
• identify the invalid parameter in the error message
• cover both validation paths in the existing parameter update test

Root cause

Parameters have no shooting-node dimension, but their bounds and initial guesses were accepted with time-dependent interpolation types. In particular, omitting the interpolation for a BoundsList silently selected CONSTANT_WITH_FIRST_AND_LAST_DIFFERENT, which is not meaningful for a parameter.

Validation

• MPLCONFIGDIR=/private/tmp/bioptim-mpl-863 python -m pytest tests/shard6/test_update_bounds_and_init.py::test_update_bounds_and_init_with_param -q (2 passed)
• git diff --check

Closes #863

---

This change is 

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.86%. Comparing base (89c83a3) to head (27de531).
⚠️ Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1067      +/-   ##
==========================================
+ Coverage   77.26%   77.86%   +0.60%     
==========================================
  Files         196      196              
  Lines       21506    21507       +1     
==========================================
+ Hits        16616    16747     +131     
+ Misses       4890     4760     -130     

Flag	Coverage Δ
unittests	77.86% <100.00%> (+0.60%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[mickaelbegon]

Codex analysis

This PR is part of Wave 2 and is rebased onto current master (e8fbc729). It rejects time-dependent interpolation for parameter bounds and initial guesses, with the invalid parameter named in the error.

CI exposed one related NMPC path: the internal one-cycle Solution builder labeled a parameter as EACH_FRAME. Codex corrected it to CONSTANT, which matches the parameter semantics within a cycle and preserves the public validation requested by #863.

Review isolation: the PR changes the parameter-validation path, the NMPC one-cycle initializer, and its focused test file; it has no source-file overlap with #1062 or #1065.

Validation completed by Codex:

• macOS, Python 3.14 / CasADi 3.7.2: tests/shard6/test_update_bounds_and_init.py — 47 passed
• existing NMPC parameter regression — 1 passed
• GitHub Actions: 23/23 checks passed
• git diff --check passed

@EveCharbie @pariterre, all local and online checks are green. This PR is ready for review as an independent Wave 2 change.