Investigate and fix number separators usage on crowdfund page

[rockstardev]

In some European cultures, like German, where the number separators are inverted, we may encounter problems with how values are displayed on the crowdfunding page:

In this instance, the amount should be shown as 7.500,00 instead of 7.500.00 in German formatting.

[bc1cindy]

Hey @rockstardev!

I've opened PR #6865 to fix this. The issue was that formatAmount was mixing locale-specific thousand separators with hardcoded decimal points.

The fix replaces the manual string manipulation with proper Intl.NumberFormat usage, so German users will now see 7.500,00 instead of 7.500.00.

Should work for all locales automatically now.

[rockstardev]

Thanks for PR @bc1cindy and your first contribution. In future in PR you can do Resolves: #6863 to automatically close issue once merged 🙏