Feature: Support all transport_opts in connect_options for WebSocket connections

[marisradu]

Problem

Currently, AbsintheClient.WebSocket only passes the :timeout option from :connect_options to the underlying Mint WebSocket connection. This limits users who need to configure other transport-level options, such as SSL verification settings.

Solution

Modified run_ws_options/1 to extract and pass through all transport_opts from :connect_options to Slipstream's mint_opts, while maintaining the default 30,000ms timeout for backwards compatibility.

Use Cases

This change enables several important scenarios:

1. Development/Testing: Disable SSL verification for local testing

   connect_options: [transport_opts: [verify: :verify_none]]

2. Production SSL: Custom certificates and certificate authorities

   connect_options: [
     transport_opts: [
       verify: :verify_peer,
       cacertfile: "/path/to/ca.pem"
     ]
   ]

3. mTLS: Client certificate authentication

   connect_options: [
     transport_opts: [
       certfile: "/path/to/client-cert.pem",
       keyfile: "/path/to/client-key.pem"
     ]
   ]

4. Performance Tuning: Socket-level options

   connect_options: [
     transport_opts: [
       nodelay: true,
       keepalive: true
     ]
   ]

Changes

• Extract full transport_opts keyword list from :connect_options
• Pass all transport options to Slipstream configuration
• Maintain default 30,000ms timeout if not specified

Testing

• ✅ Existing tests pass
• ✅ Manually tested with SSL disabled
• ✅ Backwards compatible with existing code
• ✅ Tested with erlang 27.1.2 / elixir 1.19.1-otp-27

Backwards Compatibility

✅ Fully backwards compatible - existing code continues to work unchanged

[mcrumm]

This module runs doctests so we need to change the syntax here so that this block is not treated as a test.

Suggested change

	iex> req = Req.new(base_url: "https://secure-api.example.com") |> AbsintheClient.attach()
	iex> {:ok, ws} = req |> AbsintheClient.WebSocket.connect(
	...> connect_options: [
	...> transport_opts: [
	...> verify: :verify_peer,
	...> cacertfile: "/path/to/ca.pem",
	...> certfile: "/path/to/client-cert.pem",
	...> keyfile: "/path/to/client-key.pem"
	...> ]
	...> ]
	...> )
	iex> ws |> GenServer.whereis() |> Process.alive?()
	> req = Req.new(base_url: "https://secure-api.example.com") |> AbsintheClient.attach()
	> {:ok, ws} = req |> AbsintheClient.WebSocket.connect(
	> connect_options: [
	> transport_opts: [
	> verify: :verify_peer,
	> cacertfile: "/path/to/ca.pem",
	> certfile: "/path/to/client-cert.pem",
	> keyfile: "/path/to/client-key.pem"
	> ]
	> ]
	> )
	> ws |> GenServer.whereis() |> Process.alive?()