[Frontend/Feature] Export Full Scan History as CSV (Closes #54)

[jpdevhub]

Problem

Issue #54 requests a CSV export feature. Users who scan frequently want to download their history for personal records or to import into Excel.

Goal

Add a single 'Export CSV' button to the Scan History section of ResultsPage.tsx that downloads all scan records as a .csv file.

Acceptance Criteria

• 'Export CSV' button appears in the scan history section header (only when there are > 0 scans)
• CSV columns: Date, Time, Scan ID, Grade, Freshness Score, Species, Market, City
• CSV filename: freshscan-history-{YYYY-MM-DD}.csv
• Export is client-side only (no server call needed) — uses existing scans state from ResultsPage
• Uses the Blob + URL.createObjectURL browser API (no external library needed)
• Translation key added: results.exportCsv in en.json, hi.json, bn.json
• Works on mobile (triggers native file download)

Implementation Hint

const blob = new Blob([csvString], { type: 'text/csv' });
const url = URL.createObjectURL(blob);
const a = document.createElement('a');
a.href = url; a.download = filename; a.click();

[arcgod-design]

Hi @jpdevhub! I'd love to implement this feature as part of SSoC 2026. I'm @arcgod-design.

My Approach:

• Add an "Export CSV" button on the scan history page
• Collect all scan history entries from the Supabase database for the authenticated user
• Convert the scan records (date, fish type, freshness score, confidence, location) into CSV format using the Blob API pattern shown in the implementation hint
• Trigger a browser download with a timestamped filename like scan-history-2026-06-28.csv
• Handle empty history gracefully with a user-friendly message

Could you please assign this issue to me? Ready to start immediately!

[Shriraj888]

i would like to work on this issue ,under SSoC 26 /assign

[Ankit-cs]

/attempt #180

[Ankit-cs]

please check it jpdevhub

[Ankit-cs]

please check it jpdevhub

[Ankit-cs]

please check it jpdevhub