refactor: update app module imports, enhance PWA support, and improve…

[D240021]

Issue

Closes #48

Summary

This work delivers a mobile-first dashboard with offline-capable core flows, local persistence (IndexedDB via Dexie), automatic sync when connectivity returns, and PWA support (service worker + web app manifest). The goal is to let farmers view progress, vault balances, and AI-related content without a network connection, with data reconciled when back online.

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What was implemented

Progressive Web App (PWA)

• Integrated @ducanh2912/next-pwa (Workbox under the hood) in next.config.ts.
• Added public/manifest.json and public/icons/icon.svg for installability and theming.
• Configured fallbacks.document to /offline so navigation has a precached offline fallback when both network and cache miss.
• Next.js 16 defaults to Turbopack; dev and build scripts use --webpack so the PWA plugin (webpack-based) runs correctly.
• Service worker is disabled in development; use npm run build + npm run start to test the full PWA.

Local storage & IndexedDB (Dexie)

• Added dexie with a dedicated database (harvest-finance-offline) storing:
  • Cached seasonal tips API responses
  • Vault snapshots (serializable vault rows + icon keys)
  • AI chat messages and last insights for offline display
  • Sync queue entries for deferred actions (e.g. chat while offline)
  • Client id and last sync metadata

Synchronization

• POST /api/v1/sync: server-side merge with last-write-wins using per-resource timestamps (seasonalTipsAt, vaultsAt, aiAt), persisting merged state under the Next.js app’s data/ directory (file-backed; suitable to replace with PostgreSQL/Supabase/Nest later).
• pushSync() runs when the app detects online again (useOfflineSync + useOnlineStatus).

Mobile-oriented UI (dashboard area)

• DashboardShell: mobile header, touch-friendly targets, safe-area padding, slide-out navigation drawer wired to the menu button (previously non-functional on small screens).
• OfflineIndicator: clear online/offline status for users.
• Dashboard page layout tuned for small screens (spacing, full-width primary actions where appropriate).

Feature wiring

• Seasonal tips: loads from IndexedDB first; on network failure, falls back to cached tips if available.
• Vault overview: aligned with VaultCard; loads/saves default vault list to IndexedDB for offline viewing; deposit/withdraw modals guard against vault === null during SSR/prerender.
• AI assistant: persists chat to IndexedDB; offline sends enqueue sync items and shows a message using cached insights when possible; successful online responses are saved locally.

Supporting / repo fixes (needed for a clean build)

• Resolved merge conflicts in backend app.module.ts and frontend portfolio/page.tsx.
• Added clsx and tailwind-merge (used by cn()).
• Adjusted a few UI prop types (e.g. Card/Badge variants, Stack gap vs spacing) and Stellar Freighter API usage (getPublicKey → getAddress).
• Minor fixes so TypeScript and static generation succeed (e.g. modals with nullable vault).

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How to verify

1. npm run build && npm run start in the frontend.
2. Open the dashboard, then DevTools → Network → Offline and reload; cached shell and stored data should still be usable.
3. Check Application → IndexedDB → harvest-finance-offline for stored records.
4. Toggle back online and confirm /api/v1/sync requests in the Network tab when sync runs.

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Out of scope / follow-ups

• Supabase/PostgreSQL and NestJS conflict APIs are described in the original issue as the long-term backend; this iteration implements sync on the Next.js API with a file store as a concrete, testable contract that can be swapped for a real DB later.
• Background Sync API (browser background sync) is not fully custom-implemented; online event + explicit pushSync() covers “sync when connectivity is restored” for this codebase.

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#77	🚀 Issue #48 — Mobile-First Offline Dashboard	Link to this issue

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[vic-Gray]

@D240021 pls resolve conflicts