[RomApp] Deployment of ANN Enhanced ROMs (no RomManager)

[Rbravo555]

📝 Description

ANN-enhanced ROMs (galerkin_ann, lspg_ann) could only be run through the RomManager, because the network and basis were read from its database. This PR lets them run without it, reading everything from the ROM folder.

To run standalone, the ROM folder needs:

• RightBasisMatrix.npy
• SingularValues.npy (the singular values used to scale the basis during training)
• model_weights.npy
• RomParameters.json with "ann_enhanced_settings": {"modes": [n_inf, n_sup]}

These files can come from a network trained outside the RomManager, or from the new export method.

🆕 Changelog

• rom_nn_interface.py: added NN_ROM_Interface.FromNumpyFiles(rom_data_folder, modes), which builds the interface from the files above. The database constructor is unchanged.
• rom_analysis.py: when no interface is passed, it builds one from the ROM folder using ann_enhanced_settings in RomParameters.json.
• rom_manager.py: added ExportAnnEnhancedRom, which writes a trained model to a standalone folder.
• Tests:
  • testFluidGalerkinRom2D_ANN_Standalone runs a stored model without a database.
  • testFluidGalerkinRom2D_ANN_Export exports a model with the RomManager and runs it standalone.

[NicolasSR]

Looks ready to merge