refactor: guard console.error calls behind DEV environment check

[bh462007]

Related Issue

Closes #212

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Summary

This PR updates the context files to ensure console.error() is only executed during development. The logs are now wrapped with import.meta.env.DEV, preventing unnecessary error output in production while keeping the same debugging experience during local development.

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Changes

src/context/AppContext.jsx

• Wrapped the console.error call in the exchange rates fetch .catch() block.
• Wrapped the console.error call in the Supabase loadData catch block.

src/context/AuthContext.jsx

• Wrapped the console.error call in the loadSession catch block.
• Wrapped the console.error call in the signOut error handling block.
• Wrapped the console.error call in the signOut catch block.

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What Stayed the Same

• User-facing error handling remains unchanged (setAuthError, setSession(null), return false, etc.).
• The existing catch blocks and control flow are untouched.
• This change only affects when error logs are printed.

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Implementation

Before:

console.error(error);

After:

if (import.meta.env.DEV) {
  console.error(error);
}

import.meta.env.DEV is Vite's built-in environment flag. It evaluates to true while running the development server and false in production builds, so console error logs are automatically omitted from production.

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Type of Change

• Refactor (no functional changes)

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[khanirfan18]

@bh462007 fix conflicts