v0.4.1

Embedding configuration cleanup. The provider-specific Aliyun key
(aliyun_api_key / ZOT_EMBEDDING_ALIYUN_KEY) and the implicit
provider="auto" mode were leaking the multi-provider routing
implementation into the user-facing config without a symmetrical
counterpart for Jina. Single-provider, single-key surface is cleaner.

Changed

• [embedding] provider default is now "jina" (was "auto"). Set
  provider = "aliyun" (or ZOT_EMBEDDING_PROVIDER=aliyun) to use
  Aliyun DashScope.

Removed (Breaking, very rare)

• [embedding] aliyun_api_key config key — use the unified
  [embedding] api_key instead.
• ZOT_EMBEDDING_ALIYUN_KEY env var — use ZOT_EMBEDDING_KEY instead.
• provider = "auto" mode — pick a provider explicitly.

If you upgraded to 0.4.0 within the past hour and were already using
the Aliyun-specific key, rename it to api_key /
ZOT_EMBEDDING_KEY and set provider = "aliyun".