Replace map with vector to remove key-pair restriction for System data

[boulderdaze]

Waiting for #891 to be reveiwed/merged

Systems.others_ is intended to store the data that are not species, such as mode specific number concentration. But because it is implemented as a map, for example, mode-specific density can not be stored alongside number concentration.
This PR replaces the map with a vector, removing key-pair restriction.

// current
system.others_[AEROSOL.AITKEN] = NUMBER_CONCENTRATION
system.others_[AEROSOL.AITKEN] = DENSITY

// this PR
AEROSOL.AITKEN.NUMBER_CONCENTRATION
AEROSOL.AITKEN.DENSITY

[Copilot]

Pull request overview

This PR refactors System.others_ from a map to a vector structure to support storing multiple properties (e.g., number concentration and density) for the same aerosol mode. Additionally, it introduces aerosol scoping functionality in ChemicalReactionBuilder to automatically prefix species names with mode and phase identifiers.

Key changes:

• Changed System.others_ from std::unordered_map<std::string, std::string> to std::vector<std::string>
• Added JoinStrings utility function for concatenating dot-separated names
• Introduced SetAerosolScope method in ChemicalReactionBuilder with mutual exclusivity enforcement

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
include/micm/system/system.hpp	Changed others_ from map to vector, updated UniqueNames() and StateSize() methods, added JoinStrings usage
include/micm/util/utils.hpp	Added new JoinStrings utility function for joining strings with dot separators
include/micm/process/chemical_reaction_builder.hpp	Added SetAerosolScope method with scoping logic, updated SetReactants and SetProducts to support scoping
include/micm/process/process_error.hpp	Added InvalidConfiguration error code and updated error message ordering
include/micm/util/error.hpp	Added MICM_PROCESS_ERROR_CODE_INVALID_CONFIGURATION constant
test/unit/system/test_system.cpp	Updated test to use vector-based API with emplace_back
test/unit/solver/test_state.cpp	Updated tests to use vector-based API with push_back
test/unit/process/test_process_configuration.cpp	Added comprehensive tests for aerosol scoping functionality
test/unit/process/CMakeLists.txt	Registered new aerosol scope test

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.02985% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.66%. Comparing base (33e7f7a) to head (9147b0d).

Files with missing lines	Patch %	Lines
include/micm/process/process_error.hpp	33.33%	2 Missing ⚠️
include/micm/process/chemical_reaction_builder.hpp	97.36%	1 Missing ⚠️
include/micm/util/utils.hpp	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #894      +/-   ##
==========================================
+ Coverage   94.36%   94.66%   +0.29%     
==========================================
  Files          65       66       +1     
  Lines        3197     3245      +48     
==========================================
+ Hits         3017     3072      +55     
+ Misses        180      173       -7     

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