feat(docker): add flexible LLM provider configuration

- Support LLM_PROVIDER env var to override default provider (openai/gpt-4o-mini)
- Add optional 'provider' parameter to API endpoints for per-request overrides
- Implement provider validation to ensure API keys exist
- Update documentation and examples with new configuration options

Closes the need to hardcode providers in config.yml

deploy/docker/job.py

@@ -36,6 +36,7 @@ class LlmJobPayload(BaseModel):
     q:      str
     schema: Optional[str] = None
     cache:  bool = False
+    provider: Optional[str] = None
 
 
 class CrawlJobPayload(BaseModel):
@@ -61,6 +62,7 @@ async def llm_job_enqueue(
         schema=payload.schema,
         cache=payload.cache,
         config=_config,
+        provider=payload.provider,
     )