Add support for z.ai provider for claude code

[mostlygeek]

Add an option for z.ai support for claude code. The aperture config would look like:

"zai_ant": {
	"baseurl": "https://api.z.ai/api/anthropic",
	"apikey":  "api-key-from-z.ai",
	"models": [
		"glm-5.1",
		"glm-5-turbo",
		"glm-4.7",
	],
	"compatibility": {
		"anthropic_messages": true,
		"openai_chat":        false,
	},
},

[mostlygeek]

Oops too much stuff made it into this PR. Closing and creating a new PR.