refactor(express): add union operationId types to handleDecrypt and h…

[rishikeshdadam136]

TICKET-234

Context - https://bitgo.slack.com/archives/C057BHBRG4B/p1764020095794829?thread_ts=1764018507.602879&cid=C057BHBRG4B

Summary

1. handleDecrypt and handleEncrypt in clientRoutes.ts are each registered for both v1 and v2 routes (express.v1.decrypt/express.decrypt and express.v1.encrypt/express.encrypt), but their parameter types previously only referenced the v2 operationId.
2. Updated both handlers to use the union type ('express.v1.decrypt' | 'express.decrypt' and 'express.v1.encrypt' | 'express.encrypt') so the TypeScript type accurately reflects both route registrations.

Why this matters
Without the union type, TypeScript only validates the handler against the v2 schema. If v1 and v2 schemas ever diverge (e.g. different request body fields), the v1 registration would silently accept a handler that is only type-safe for v2, leading to potential runtime bugs with no compile-time warning.

Both the end points are splitted in these pr's:#8560
#8553

[linear]

WCI-234 Add union operationId types to handleDecrypt and handleEncrypt handlers

[lokesh-bitgo]

looks good