feat: add web dashboard workflow and report history

## Summary

- Add FastAPI backend for dataset upload, metric pre-check, analysis, results, and reports

- Add React-based web dashboard with Data Upload, Analysis, Metric Detail, and Reports tabs

- Add user-defined metric weights and weighted overall quality score calculation

- Add metric-specific detail pages for Completeness, Accuracy, Consistency, Timeliness, Reliability, and Uniqueness

- Add PDF/Excel report export

- Add SQLite-backed report history with rename/delete support

- Refactor data quality helper logic for dashboard summary and detail views

## Test

- Uploaded CSV dataset and checked preview table

- Verified metric pre-check and metric configuration flow

- Ran data quality analysis with selected metrics and weights

- Checked Analysis Summary and metric detail pages

- Verified PDF/Excel report download

- Verified report history persistence, rename, and delete actions