fix: route P2P deposits and verification to Asset Hub instead of relay chain

DepositModal was building transactions via relay chain API, and all three
edge functions (verify-deposit, process-withdraw, process-withdrawal) had
RPC endpoints hardcoded or defaulting to the relay chain. This caused
deposit verification to fail with "Transaction not yet finalized" and
created a chain mismatch with the withdrawal system which operates on
Asset Hub.

- DepositModal: use assetHubApi instead of api for transfer TX
- verify-deposit: RPC_HTTP/RPC_WS default to asset-hub-rpc (env override)
- process-withdraw: RPC_ENDPOINT default to asset-hub-rpc (env override)
- process-withdrawal: RPC_ENDPOINT default to asset-hub-rpc

web/supabase/functions/process-withdraw/index.ts

@@ -26,8 +26,8 @@ function getCorsHeaders(origin: string | null) {
 // Platform hot wallet address
 const PLATFORM_WALLET = '5HN6sFM7TbPQazmfhJP1kU8itw7Tb2A9UML8TwSYRwiN9q5Z'
 
-// RPC endpoint
-const RPC_ENDPOINT = 'wss://rpc.pezkuwichain.io'
+// RPC endpoint — defaults to Asset Hub where user balances live
+const RPC_ENDPOINT = Deno.env.get('RPC_ENDPOINT') || 'wss://asset-hub-rpc.pezkuwichain.io'
 
 // Token decimals
 const DECIMALS = 12