[Task] Audit and fix frontend console.error / silent catch handling

[Megha-Dev-19]

Review all console.error and catch-without-proper-handling across the frontend, and fix them according to the guidance in .github/copilot-instructions.md (Frontend Error Reporting) and .cursor/rules/frontend-error-reporting.mdc.

Use reportError from nt-fe/lib/report-error.ts for Sentry + logging.

Scope

• Audit nt-fe for console.error and empty / silent catch blocks
• Classify each case:
  • User-blocking → toast + reportError
  • Best-effort / background → reportError only (no toast)
  • Already handled upstream → keep as-is or simplify
• Fix high-traffic / wallet-critical paths first (near-store, payments, exchange, settings, proposals, wallet)
• Avoid double toasts where the store already surfaces a wallet error