Add OpenAI JSON Schema (structured output) support to $gpt

[Copilot]

The OpenAI provider lacked support for the response_format: json_schema mode, which enforces server-side schema validation and guarantees structured JSON output from the model.

Changes

js/owrap.ai.js

• rawResponse (OpenAI provider) — new low-level method mirroring rawPrompt but sets response_format: { type: "json_schema", json_schema: { name, description, schema, strict } }. Integrates with conversation history, debug channels, and stats capture. Defaults: description → "API Response", strict → true.

• jsonSchemaPrompt(aPrompt, aResponseSchema, aModel, aTemperature, tools) — prototype method that calls rawResponse and returns the parsed JSON. Throws for providers that don't implement rawResponse.

• jsonSchemaPromptWithStats(...) — same, returns { response, stats }.

• $gpt.jsonSchemaPrompt / $gpt.jsonSchemaPromptWithStats — convenience wrappers on the global $gpt object.

tests/autoTestAll.AI.{js,yaml}

Five new unit tests (all using mock _request): raw request structure, response parsing, stats capture, schema defaults, and unsupported-provider error.

Usage

var result = $gpt({ type: "openai", options: { key: "sk-...", model: "gpt-4o" } })
    .jsonSchemaPrompt("Extract: Alice, alice@example.com, 30", {
        name: "PersonInfo",
        description: "Extract person details",
        schema: {
            type: "object",
            properties: {
                name:  { type: "string" },
                email: { type: "string" },
                age:   { type: "number" }
            },
            required: ["name", "email"],
            additionalProperties: false
        },
        strict: true
    })
// → { name: "Alice", email: "alice@example.com", age: 30 }