feat(llm): add iFlytek Spark (Astron MaaS) provider

[FenjuFu]

What

Adds iflytek to LLM_PROVIDER_REGISTRY: iFlytek Spark served by iFlytek's Astron MaaS platform, which exposes OpenAI-compatible Chat Completions. Registry metadata only, adapter stays openai_compatible, no new request path. It sits in the 主流模型原厂与云厂商 group right after Xiaomi MiMo, next to the other first-party Chinese model vendors.

file	change
app/models/llm_provider.py	11 lines after mimo: default model spark-x2.5, default base URL https://maas-api.cn-huabei-1.xf-yun.com/v2
config.example.toml	iflytek_api_key / iflytek_base_url / iflytek_model_name
webui/i18n/en.json, webui/i18n/zh.json	tips, using only the existing {api_key_url} / {default_base_url} / {default_model} / {model_docs_url} placeholders; the label comes from the registry like mimo and minimax
test/services/test_llm.py	registry assertions, "iflytek" in the group-order test, and a client test for the default and a saved Token Plan base URL

Two endpoints, one provider

Astron MaaS has a pay-as-you-go endpoint (maas-api…/v2, the default here) and a Token Plan endpoint (maas-token-api…/v2). Keys are tied to one of them, so a Token Plan key sent to the default endpoint gets iFlytek's 403 11200 no valid authorization. Rather than add a second provider id, the tips and the config example tell Token Plan users to put the Token Plan URL in Base Url; the existing override handling keeps it as-is, which the new test covers.

Spark X2.5 is a reasoning model. Its reasoning comes back in reasoning_content, separate from content, so the existing _extract_chat_completion_text path already returns only the answer.

Checked today (2026-10-03) with a real Token Plan key

• llm.generate_script(video_subject="why the sky is blue", paragraph_number=1) through _generate_response with iflytek_base_url set to the Token Plan URL: a clean one-paragraph script in about 45 s.
• llm.generate_terms(...) on that script: ['Why sky blue', 'Blue sky cause', 'Sky blue scattering', 'Blue sky rayleigh', 'Blue sky atmosphere'].
• The same key on the default pay-as-you-go endpoint returns the 403 above, which is the behaviour the tips describe. I don't have a pay-as-you-go key with an active order, so the default endpoint was not exercised end to end.

Locally (uv sync --frozen --python 3.11, Windows): test/services/test_llm.py and test/services/test_webui_i18n.py pass (131 passed, 1 skipped), ruff check app cli.py main.py webui test docs/skill is clean. In the full suite 8 tests in the cache-manager, material, ElevenLabs music and Sonilo modules fail, and they fail the same way on main without this change.

Disclosure: I'm a member of the iFlytek Astron open-source community. No pricing or referral links are in the diff.

[harry0703]

Thanks for adding iFlytek Spark support and the clear configuration instructions! Merged — appreciate your contribution.