Use browser timeout for async target registration

[Copilot]

Ruby 3.3 CI was failing in Tests (3.3) because page creation could raise Ferrum::NoSuchTargetError while waiting for Target.createTarget to be reflected back through async target events. The wait path was using the low-level protocol timeout instead of the normal browser operation timeout.

• Root cause

  • Ferrum::Context#create_target waited for target registration with @client.protocol_timeout
  • That timeout is tuned for direct CDP request/response bookkeeping, not for async Target.* event delivery and processing

• Change

  • Switch target registration waiting to the browser timeout budget:

    resolved = pending.value(@client.options.timeout)

  • This keeps protocol_timeout scoped to transport-level CDP calls while allowing target creation to complete under normal page-operation timing

• Regression coverage

  • Add a focused spec for Ferrum::Context#create_target
  • The spec uses a tiny protocol_timeout and a larger browser timeout, then resolves add_target asynchronously to verify create_target waits on the correct timeout source