Dynamic template tools fail under UPLOAD_STRATEGY=LIBRECHAT

[dvejsada]

Found while writing the developer docs for #111.

What happens. Every YAML- or admin-defined Word and email template tool calls the synchronous upload_file() inside its offloaded body (docx_tools/dynamic_docx_tools.py, email_tools/dynamic_email_tools.py). upload_file() refuses the LibreChat strategy:

if UPLOAD_STRATEGY == StorageStrategy.LIBRECHAT:
    raise RuntimeError("LIBRECHAT strategy requires async upload. Use upload_file_async() instead.")

So on a LibreChat deployment the six built-in tools work and every dynamic template tool fails with ToolError("Error generating document from template <name>: LIBRECHAT strategy requires async upload…").

Why the static tools work. Their handlers in main.py read the user context on the event loop with extract_user_context_from_request() and upload through librechat_integration.upload_and_format_response(), which branches to upload_file_async() for LibreChat.

Fix. In each _register_single_*_template():

1. Make the handler read extract_user_context_from_request() on the event loop before dispatching.
2. Split _sync_impl so it returns the BytesIO and filename instead of uploading.
3. Have the async handler call upload_and_format_response(buffer, ext, filename, user_context, message, add_unique_prefix=payload.get("add_unique_prefix")), which already offloads the sync upload for the other strategies and returns the artifact dict for LibreChat.
4. Keep metrics.record_call/record_error around the whole thing.

The return annotation of the tool changes from str to Union[str, dict], matching the static tools. Add a test in tests/test_librechat_integration.py that registers a template against a fresh FastMCP() with the strategy patched to LibreChat.

Documented as a known limitation in docs/development/dynamic-templates.md and docs/development/architecture.md until fixed.