[Acados v0.5.5][1/5] Upgrade compatibility baseline

[mickaelbegon]

Context

This draft PR is the first implementation step from a Codex analysis of the
Acados v0.5.5 release and its relevant additions for Bioptim.

It upgrades the bundled Acados submodule from v0.5.1 to v0.5.5 and establishes
the compatibility baseline required by the follow-up PRs. It is intentionally
kept as WIP for maintainer review.

Changes

• update external/acados to the official v0.5.5 tag;
• migrate Bioptim to AcadosOcp.code_gen_options;
• preserve the existing c_compile=False behavior by disabling Acados'
  automatic reuse override for now;
• update Linux and macOS installers for current dependency CMake versions;
• select architecture-aware BLASFEO defaults on Linux and Apple Silicon;
• install the new Acados code-generation metadata files;
• update macOS @rpath handling for the installed libraries;
• add a focused code-generation configuration test.

Validation

• origin/master is unchanged since the branch point (e8fbc729);
• native Acados v0.5.5 configure, build, and install succeeded on macOS arm64;
• generated libraries load without DYLD_LIBRARY_PATH;
• bash -n external/acados_install_linux.sh external/acados_install_mac.sh;
• tests/shard1/test_acados_interface.py: 29 passed.

Planned follow-ups

1. This PR — compatibility baseline and v0.5.5 upgrade
2. codex/acados-v055-reuse-reset — generated-code reuse and solver reset
3. codex/acados-v055-solver-modes — relevant new solver modes/options
4. codex/acados-v055-diagnostics — richer status and diagnostic reporting
5. codex/acados-v055-runtime-parameters — runtime parameter update paths

The later branches are placeholders based on master; each will be rebased on
the preceding accepted dependency when its implementation starts.

Note for maintainers

This proposal and the five-PR decomposition come from a Codex compatibility and
feature analysis. Maintainer feedback is especially welcome on the scope and
ordering before the follow-up implementations are finalized.

---

This change is 

[mickaelbegon]

Closing this draft to reduce the active PR load. The work remains available on mickaelbegon:codex/acados-v055-upgrade and is now tracked as a Codex analysis in #1088.

[codecov]

Codecov Report

❌ Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 77.87%. Comparing base (89c83a3) to head (153a913).
⚠️ Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
bioptim/interfaces/acados_interface.py	92.85%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1087      +/-   ##
==========================================
+ Coverage   77.26%   77.87%   +0.61%     
==========================================
  Files         196      196              
  Lines       21506    21514       +8     
==========================================
+ Hits        16616    16755     +139     
+ Misses       4890     4759     -131     

Flag	Coverage Δ
unittests	77.87% <92.85%> (+0.61%)	⬆️

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