docs: overhaul documentation for fork readiness

- Rewrite README from scratch: accurate stack versions, correct setup
  sequence, verified feature list, full API reference, architecture
  overview, and security model — all sourced directly from the codebase
- Remove internal/stale docs: COLOR_SCHEME_MODERNIZATION.md, plan.md,
  frontend/README.md (CRA boilerplate)
- Clean up DESIGN_SYSTEM.md: remove emoji headers and version footer
- Fix WEEKLY_REPORT_FEATURE.md: replace hardcoded absolute paths with
  relative paths
- Clean up test_cases_auth.md: remove stale branch and date references

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

WEEKLY_REPORT_FEATURE.md

@@ -48,13 +48,13 @@ A new feature has been added to the CVE Dashboard that allows users to upload th
 
 1. **Backend:**
    ```bash
-   cd /home/admin/cve-dashboard/backend
+   cd backend
    node server.js
    ```
 
 2. **Frontend:**
    ```bash
-   cd /home/admin/cve-dashboard/frontend
+   cd frontend
    npm start
    ```