feat(growers): show sessions and wallet registration in grower card

[Jaiharishan]

Summary

• Adds a collapsible Sessions section to the grower detail drawer (after Device Identifiers), pulling from the treetracker-field-data service (session, device-configuration, wallet-registration) so reviewers can see which app/device a grower used without running manual SQL.
• Each session shows: check-in photo (if any), date, organization, device brand/model/app version, and wallet email/phone.
• New REACT_APP_FIELD_DATA_API_ROOT env var added to .env.development/.env.staging/.env.production/.env.test, verified reachable against the real dev and prod clusters.
• New src/api/fieldData.js module (fetch-based, follows existing src/api/* conventions).

Known limitation

GET /session on treetracker-field-data has no server-side filter by grower/wallet, so sessions are paged through and matched client-side by grower_account_id, and by target_wallet against the known email/phone for that grower (capped at 20 pages to keep the drawer responsive, with a console warning if the cap is hit). A proper filter param on the field-data service would remove this limitation.

Test plan

• npm run prettier / eslint clean on changed files
• New jest tests in src/components/tests/GrowerDetail.test.js (populated + empty session states) pass
• Verified manually in the dev environment: opened a grower card, expanded the new Sessions accordion, confirmed it renders correctly alongside existing sections
• src/models/ unit tests still pass

Closes #616