fix(runtime): use camelCase OpenAI-compatible provider option keys

Problem

After the AI SDK v7 upgrade in #1198, requests to Z.AI Coding Plan emit repeated deprecation warnings:

AI SDK Warning (zai-coding-plan.chat / glm-5.2): Deprecated: "providerOptions key 'zai-coding-plan'". Use 'zaiCodingPlan' instead.

The request still works because @ai-sdk/openai-compatible@3.0.12 currently accepts both forms, but it emits one warning for every model invocation. Agent/tool loops therefore produce the warning repeatedly.

Cause

buildProviderOptions currently emits the raw provider name as the options namespace:

{ 'zai-coding-plan': { reasoningEffort: 'high' } }

@ai-sdk/openai-compatible now expects camelCase provider option keys:

{ zaiCodingPlan: { reasoningEffort: 'high' } }

The current regression test explicitly pins the deprecated dashed namespace:

• packages/runtime/src/model-factory.ts
• packages/runtime/src/__tests__/model-factory-thinking.test.ts

This may also affect other OpenAI-compatible providers whose configured names contain hyphens.

Expected behavior

OpenAI-compatible provider options use the SDK's current camelCase namespace without changing the provider ID, model routing, or wire-level request fields.

Acceptance criteria

• zai-coding-plan provider options are emitted under zaiCodingPlan.
• reasoningEffort still reaches the request as reasoning_effort.
• Dashed OpenAI-compatible provider names are handled consistently rather than special-casing only Z.AI.
• Regression coverage exercises the current AI SDK parsing path and confirms that no deprecation warning is produced.