feat(express): improve typed routes validation error messages

[Marzooqa]

Summary

• Replace raw io-ts validation errors with human-readable messages in typed routes
• Add ValidationError class for consistent error handling

Before

[
    "Invalid value undefined supplied to : httpRequest/body: Exact<({ address: string, amount: (number | string) } & Partial<{ data: (string | undefined), feeLimit: (string | undefined), walletPassphrase: (string | undefined),...............Partial<{ address: string }>)> }> } & Partial<{ verification: any }>) | undefined) }>/memo: ({ value: string, type: string } | undefined)/1: undefined"
]    

After:

{
    "error": "Missing required field 'memo.value'. Missing required field 'memo.type'.",
    "message": "Missing required field 'memo.value'. Missing required field 'memo.type'.",
    "name": "ValidationError",
    "bitgoJsVersion": "...",
    "bitgoExpressVersion": "....."
}                                                                                         
   

TICKET: WP-7883

[pranavjain97]

nice work

[lokesh-bitgo]

Looks good