Add Accurate South African Rand ZAR Pricing for BTC

[pretyflaco]

Description
Please add accurate ZAR pricing for BTC in the Blink app by integrating with local exchange APIs (VALR or Luno). This will account for the South African arbitrage premium on BTC resulting from capital controls in ZA.

Context
A common issue during onboarding is the price difference due to the SA arbitrage premium. Current USD prices do not reflect the local market accurately.

Example
ZAR/USD: R18.33
BTC on local exchange: R1,245,052 ($67,924)
BTC in the US: $66,210
Difference: $1,714

Proposal
Integrate with VALR or Luno's free pricing APIs to display local ZAR prices for BTC.

Benefits

• Accurate BTC pricing for South African users
• Improved onboarding experience
• Increased app adoption in South Africa