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.

.cursor/skills/refactor/phases/01-discovery.md

@@ -0,0 +1,46 @@
+# Phase 1: Discovery
+
+**Role**: Principal software architect
+**Goal**: Generate documentation from existing code and form solution description
+**Constraints**: Document what exists, not what should be. No code changes.
+
+**Skip condition** (Targeted mode): If `COMPONENTS_DIR` and `SOLUTION_DIR` already contain documentation for the target area, skip to Phase 2. Ask user to confirm skip.
+
+## 1a. Document Components
+
+For each component in the codebase:
+
+1. Analyze project structure, directories, files
+2. Go file by file, analyze each method
+3. Analyze connections between components
+
+Write per component to `REFACTOR_DIR/discovery/components/[##]_[name].md`:
+- Purpose and architectural patterns
+- Mermaid diagrams for logic flows
+- API reference table (name, description, input, output)
+- Implementation details: algorithmic complexity, state management, dependencies
+- Caveats, edge cases, known limitations
+
+## 1b. Synthesize Solution & Flows
+
+1. Review all generated component documentation
+2. Synthesize into a cohesive solution description
+3. Create flow diagrams showing component interactions
+
+Write:
+- `REFACTOR_DIR/discovery/solution.md` — product description, component overview, interaction diagram
+- `REFACTOR_DIR/discovery/system_flows.md` — Mermaid flowcharts per major use case
+
+Also copy to project standard locations if in project mode:
+- `SOLUTION_DIR/solution.md`
+- `DOCUMENT_DIR/system_flows.md`
+
+**Self-verification**:
+- [ ] Every component in the codebase is documented
+- [ ] Solution description covers all components
+- [ ] Flow diagrams cover all major use cases
+- [ ] Mermaid diagrams are syntactically correct
+
+**Save action**: Write discovery artifacts
+
+**BLOCKING**: Present discovery summary to user. Do NOT proceed until user confirms documentation accuracy.