Refactor of the Import functionality

This is a big 'un, and might be difficult to review. I've tried to lay down the main idea below.

Why this PR

In FM2PROF 2.6 we plan to add "GIS2PROF" functionality, which comes down to:

• supporting a new input format besides dflowfm
• changing the workflow to allow for cross-section generation without hydraulic data

To lay the groundwork for this functionality, we need to do some serious plumbing work. Mainly:

1. Rewriting the import functionality such that it supports multiple formats without code duplication, and remove hardcoded references to dfm which are littered throughout the code
2. Clean-up the model-data class such that is much more clear what type of data is required when and if we have a format that's missing some stuff - and make it more testable.

• The current implementation mixed data loading, I/O and classification logic directly inside the runner class, making it hard to test classification in isolation, so we should also take the data pre-processing out of the runner class into a separate package.
• The current implementation was less explicit about what kinds of data were necessary and the type of that data (e.g. time_independent_data). The new structure makes this explicit, in prep. for a new file format that does not have hydraulic or edge data.

Finally, to lay proper groundwork, we'll:

• tackle as much dependabot and sonarcloud issues as we reasonably can.

Design plan

1. Adopt a factory-architecture like we did with the refactor of the export functionality (when we added the D-HYDRO output format).
2. (a) Rewrite FM_Model_Data into source-agnostic Model_Data with proper typing, type-checking and explicit coercing, insofar python allows us to do this. (b) yank the data preprocessing (_set_fm_model_data) out of the runner class and into a data_preprocessing module.

Refactor 1: import into dedicated package

Summary

Refactors the import functionality from data_import.py into a dedicated imports package, following the same pattern as the existing export module.

New structure:

• base.py — Abstract BaseImporter class and generalized ModelData (replacing FmModelData)
• dflowfm.py — DFlowFMImporter migrated from FMDataImporter, implementing import_data() -> ModelData
• factory.py — ImporterFactory.create(source, file_path) for source-agnostic importer instantiation
• __init__.py — Public API exports

Updated files:

• fm2prof_runner.py — Uses ImporterFactory and ModelData instead of FMDataImporter/FmModelData
• polygon_file.py — Uses ImporterFactory.create("dflowfm", ...) instead of FMDataImporter directly
• test_data_import.py — Updated to use DFlowFMImporter and ModelData

Refactor 2: source-agnostic ModelData preprocessing pipeline

Summary

Extracts all 2D model data loading and classification from Fm2ProfRunner into a dedicated, testable data_preprocessing.py module. Geometry, edge and hydraulic dataclasses now enforce correct numpy dtypes on every field assignment, preventing silent string truncation bugs.

Changes

New: data_preprocessing.py

• Introduces build_model_data(input_files, ...) as the single entry point for the initialisation pipeline
• Source-agnostic: format is selected via ImporterFactory, making it straightforward to support future input formats
• Handles region/section polygon classification, nearest-neighbour cross-section assignment, and Chézy variance-based section splitting

New: ini_file.py — InputFiles dataclass

• Convenience container grouping map_file, css_file, region_file and section_file
• IniFile.get_input_files() constructs and returns an InputFiles instance, normalising optional files to None
• Callers no longer pass four individual path arguments

Updated: base.py

• FaceGeometry, EdgeGeometry and HydraulicData declare dtype per field using field(metadata={"dtype": ...})
• Shared _ndarray_setattr reads the metadata and calls np.asarray(value, dtype=dtype) on every assignment — including post-construction mutation
• String fields (section, region, sclass) use dtype=object, preventing numpy's fixed-width <UN truncation of variable-length cross-section names

Updated: fm2prof_runner.py

• _initialise_fm2prof delegates entirely to build_model_data; legacy source-specific code removed
• Uses ini_file.get_input_files() instead of four separate get_input_file() calls
• switched from fm_model_data to source-agnostic model_data variable names

Updated: cross_sections.py

• switched from fm_model_data to source-agnostic model_data variable names

New: test_data_preprocessing.py

• TestClassification.test_region_polygon_assigns_all_faces_to_poly1 verifies that all 2D faces are assigned to region poly1 for the compound-with-region acceptance case

Updated: test_acceptance.py

• clear_polygon_caches autouse fixture deletes *_cache.json files before each test, ensuring fresh polygon classification on every run

3. Upgrade packages and security issues

• Upgraded all packages with uv lock --upgrade

  • deltares-hms-docs = { git = "https://github.com/Deltares-research/doc_utils.git", branch="latex-templates"} no longer exists on remote, so switch to the main branch.

• Add pip-audit to dev depencies, run uv run pip-audit

  • Remaining vulnerability in pytest - upgrade to >= 9.0

Upgrading caused failing test_cli tests, because click upgraded past typer. Upgraded the typer dependency in pyproject.toml