fix(aionrs): handle non-v1 OpenAI-compatible API roots for chat completions

[taekchef]

Summary

After the AionUi / AionCore repo split, the old AionUi PR iOfficeAI/AionUi#2514 no longer applies cleanly, but the runtime bug is still relevant.

Some OpenAI-compatible providers use a versioned API root that is not /v1, for example:

• Zhipu: https://open.bigmodel.cn/api/paas/v4
• Ark: https://ark.cn-beijing.volces.com/api/v3
• Qianfan: https://qianfan.baidubce.com/v2

When these providers are used through AionRS, the request can become:

/api/paas/v4/v1/chat/completions

Expected:

/api/paas/v4/chat/completions

Current code after the split

AionUi still owns the preset provider list, but AionRS runtime URL resolution now lives in AionCore.

Relevant current AionCore behavior:

• resolve_aionrs_url_and_compat() handles:
  • is_full_url
  • Gemini /v1beta/openai
  • official OpenAI max_completion_tokens
• It does not yet set compat.api_path = "/chat/completions" for known non-/v1 OpenAI-compatible roots.
• crates/aionui-system/src/model_fetcher/url_fixer.rs already knows these roots for model fetching: /v2, /api/v3, /api/paas/v4.

Proposed fix

In AionCore, when the mapped provider is openai and the base URL path ends with one of the known non-/v1 API roots:

• /api/paas/v4
• /api/v3
• /v2

set:

compat.api_path = Some("/chat/completions".to_owned());

Keep existing behavior unchanged for:

• official OpenAI /v1
• DeepSeek and other normal /v1 OpenAI-compatible providers
• Gemini
• is_full_url = true

Acceptance criteria

• Zhipu /api/paas/v4 resolves to root chat completions path.
• Ark /api/v3 resolves to root chat completions path.
• Qianfan /v2 resolves to root chat completions path.
• Trailing slash variants are covered.
• Official OpenAI /v1 does not get this override.
• Existing is_full_url behavior from AionCore#307 remains unchanged.

Related:

• Old PR: fix: set AionRS chat completions path for non-v1 OpenAI-compatible providers AionUi#2514
• User reports: [Bug]: Error when using GLM coding plan AionUi#2713, [Bug]: Z.AI GLM Coding Plan not usable with AionUI always 404 Error AionUi#2854