Refactor constants management to use Pydantic BaseModel for configuration

- Replaced module-level path variables in constants.py with a structured Pydantic Config class.
- Updated all relevant modules (train.py, augmentation.py, exports.py, dataset-visualiser.py, manual_run.py) to access paths through the new config structure.
- Fixed bugs related to image processing and model saving.
- Enhanced test infrastructure to accommodate the new configuration approach.

This refactor improves code maintainability and clarity by centralizing configuration management.

_docs/02_document/modules/dto_annotationClass.md

@@ -0,0 +1,49 @@
+# Module: dto/annotationClass
+
+## Purpose
+Defines the `AnnotationClass` data model and `WeatherMode` enum used in the training pipeline. Reads annotation class definitions from `classes.json`.
+
+## Public Interface
+
+### WeatherMode (Enum)
+| Member | Value | Description |
+|--------|-------|-------------|
+| `Norm` | 0 | Normal weather |
+| `Wint` | 20 | Winter conditions |
+| `Night` | 40 | Night conditions |
+
+### AnnotationClass
+| Field/Method | Type/Signature | Description |
+|-------------|----------------|-------------|
+| `id` | int | Class ID (weather_offset + base_id) |
+| `name` | str | Class name (with weather suffix if non-Norm) |
+| `color` | str | Hex color string (e.g. `#ff0000`) |
+| `color_tuple` | property → tuple | RGB tuple parsed from hex color |
+| `read_json()` | static → dict[int, AnnotationClass] | Reads `classes.json`, expands across weather modes, returns dict keyed by ID |
+
+## Internal Logic
+- `read_json()` locates `classes.json` relative to the parent directory of the `dto/` package
+- For each of the 3 weather modes, creates an AnnotationClass per entry in `classes.json` with offset IDs (0, 20, 40)
+- This produces up to 80 classes total (17 base × 3 modes = 51, but the system reserves 80 slots)
+- `color_tuple` strips the first 3 characters of the color string and parses hex pairs
+
+## Dependencies
+- `json`, `enum`, `os.path` (stdlib)
+
+## Consumers
+train (for YAML generation), dataset-visualiser (for visualization colors)
+
+## Data Models
+`AnnotationClass` — annotation class with ID, name, color. `WeatherMode` — enum for weather conditions.
+
+## Configuration
+Reads `classes.json` from project root (relative path from `dto/` parent).
+
+## External Integrations
+None.
+
+## Security
+None.
+
+## Tests
+None directly; used transitively by `tests/imagelabel_visualize_test.py`.