docs: add RERANKER_ZEROENTROPY_BASE_URL to configuration page

Document the new configurable base URL for the ZeroEntropy reranker
provider added in #766. Also fix a type error where RERANK_URL was
renamed to rerank_url but one usage was missed.

hindsight-api-slim/hindsight_api/engine/cross_encoder.py

@@ -704,7 +704,7 @@ class ZeroEntropyCrossEncoder(CrossEncoderModel):
             indices = [idx for idx, _ in indexed_texts]
 
             response = await self._async_client.post(
-                self.RERANK_URL,
+                self.rerank_url,
                 json={
                     "model": self.model,
                     "query": query,

hindsight-docs/docs/developer/configuration.md

@@ -464,6 +464,7 @@ Supported OpenAI embedding dimensions:
 | `HINDSIGHT_API_RERANKER_LITELLM_MAX_TOKENS_PER_DOC` | Truncate documents to this many tokens before sending to the reranker (applies to both `litellm` and `litellm-sdk`). Use for models with small context windows (e.g. set to `900` for a 1024-token limit model). Unset by default (no truncation). | - |
 | `HINDSIGHT_API_RERANKER_ZEROENTROPY_API_KEY` | ZeroEntropy API key for reranking | - |
 | `HINDSIGHT_API_RERANKER_ZEROENTROPY_MODEL` | ZeroEntropy rerank model (`zerank-2`, `zerank-2-small`) | `zerank-2` |
+| `HINDSIGHT_API_RERANKER_ZEROENTROPY_BASE_URL` | Custom base URL for ZeroEntropy-compatible API (e.g., mock server, proxy, or self-hosted deployment) | `https://api.zeroentropy.dev` |
 | `HINDSIGHT_API_RERANKER_FLASHRANK_MODEL` | FlashRank model for fast CPU-based reranking | `ms-marco-MiniLM-L-12-v2` |
 | `HINDSIGHT_API_RERANKER_FLASHRANK_CACHE_DIR` | Cache directory for FlashRank models | System default |
 | `HINDSIGHT_API_RERANKER_JINA_MLX_MODEL_PATH` | Local path to downloaded `jina-reranker-v3-mlx` model (auto-downloads from HuggingFace if unset) | - |
@@ -498,6 +499,7 @@ export HINDSIGHT_API_RERANKER_COHERE_BASE_URL=https://your-azure-cohere-endpoint
 export HINDSIGHT_API_RERANKER_PROVIDER=zeroentropy
 export HINDSIGHT_API_RERANKER_ZEROENTROPY_API_KEY=your-api-key
 export HINDSIGHT_API_RERANKER_ZEROENTROPY_MODEL=zerank-2  # or zerank-2-small
+# export HINDSIGHT_API_RERANKER_ZEROENTROPY_BASE_URL=https://your-custom-endpoint.com  # optional
 
 # LiteLLM proxy - unified gateway for multiple reranking providers (requires running LiteLLM proxy server)
 export HINDSIGHT_API_RERANKER_PROVIDER=litellm