feat: Implement CSV schema validation and initial data import (!14) · Merge requests · coll0155 / Chavost

Refactored data loading to include schema coercion and validation in _coerce_and_validate.
Added a first-run setup UI for importing a CSV file if the data file is missing.
Enhanced error handling for invalid CSV files during import.
Introduced functionality to replace the existing dataset via the tools interface.
Updated the onboarding instructions to reflect the new data import process.

feat: Implement CSV schema validation and initial data import