chore: remove remote::passthrough inference provider (#6368)

Remove the remote::passthrough provider, its registry entry, and all
supporting code: the passthrough module (passthrough.py, config.py,
__init__.py), the forward_headers utility module, the unit test suite,
and documentation files.

Update the codex CLI test to use a generic api_key instead of
passthrough_api_key since X-OGX-Provider-Data forwarding is a generic
mechanism not tied to any one provider.

Signed-off-by: Matthew Farrellee <matt@cs.wisc.edu>

Author: mattf

docs/docs/distributions/self_hosted_distro/passthrough.md

@@ -74,7 +74,6 @@
     "meta",
     "nvidia",
     "oci",
-    "passthrough",
     "runpod",
     "sambanova",
 }

docs/docs/providers/inference/remote_passthrough.mdx

@@ -267,16 +267,6 @@ def available_providers() -> list[ProviderSpec]:
             provider_data_validator="ogx.providers.remote.inference.sambanova.config.SambaNovaProviderDataValidator",
             description="SambaNova inference provider for running models on SambaNova's dataflow architecture.",
         ),
-        RemoteProviderSpec(
-            api=Api.inference,
-            adapter_type="passthrough",
-            provider_type="remote::passthrough",
-            pip_packages=[],
-            module="ogx.providers.remote.inference.passthrough",
-            config_class="ogx.providers.remote.inference.passthrough.PassthroughImplConfig",
-            provider_data_validator="ogx.providers.remote.inference.passthrough.PassthroughProviderDataValidator",
-            description="Passthrough inference provider for connecting to any external inference service not directly supported.",
-        ),
         RemoteProviderSpec(
             api=Api.inference,
             adapter_type="watsonx",

scripts/generate_target_models_docs.py

@@ -21,7 +21,6 @@ remote/
     oci/               # Oracle Cloud Infrastructure
     ollama/            # Ollama
     openai/            # OpenAI
-    passthrough/       # Generic passthrough to any endpoint
     runpod/            # RunPod
     sambanova/         # SambaNova
     together/          # Together AI

src/ogx/providers/registry/inference.py

@@ -19,7 +19,6 @@ inference/
   oci/                 # Oracle Cloud Infrastructure GenAI
   ollama/              # Ollama (local model serving)
   openai/              # OpenAI API
-  passthrough/         # Generic passthrough to any endpoint
   runpod/              # RunPod cloud GPU
   sambanova/           # SambaNova
   tgi/                 # HuggingFace TGI and Inference API