OpenAI Responses image content blocks do not support file_id inputs

### Submission checklist - [x] This is a bug, not a usage question. - [x] I added a clear and descriptive title that summarizes this issue. - [x] I used the GitHub search to find a similar question and didn't find it. - [x] I am sure that this is a bug in LangChain rather than my code. - [x] The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package). - [x] This is not related to the langchain-community package. - [x] I posted a self-contained, minimal, reproducible example. A maintainer can copy it and run it AS IS. ### Package (Required) - [ ] langchain - [x] langchain-openai - [ ] langchain-anthropic - [ ] langchain-classic - [x] langchain-core - [ ] langchain-model-profiles - [ ] langchain-tests - [ ] langchain-text-splitters - [ ] langchain-chroma - [ ] langchain-deepseek - [ ] langchain-exa - [ ] langchain-fireworks - [ ] langchain-groq - [ ] langchain-huggingface - [ ] langchain-mistralai - [ ] langchain-nomic - [ ] langchain-ollama - [ ] langchain-openrouter - [ ] langchain-perplexity - [ ] langchain-qdrant - [ ] langchain-xai - [ ] Other / not sure / general ### Related Issues / PRs I did not find an existing issue or PR for OpenAI Responses image file_id conversion. Related but different scope: #33652 covers video conversion. ### Reproduction Steps / Example Code (Python) ```python from langchain_core.messages import content as types from langchain_core.messages.block_translators.openai import convert_to_openai_data_block block = types.create_image_block(file_id="file-abc123") # Expected: {"type": "input_image", "file_id": "file-abc123"} print(convert_to_openai_data_block(block, api="responses")) ``` ### Error Message and Stack Trace (if applicable) ```shell ValueError: Unsupported source type. Only 'url' and 'base64' are supported. ``` ### Description ImageContentBlock supports image inputs by file_id, but the OpenAI Responses block translator currently routes image blocks through the URL/base64 conv…