feat: Add OPENHANDS_FORCE_VISION env var to override vision capability detection (#10255)

Co-authored-by: mamoodi <mamoodiha@gmail.com>
Co-authored-by: Engel Nyst <engel.nyst@gmail.com>

openhands/llm/llm.py

@@ -515,6 +515,16 @@ class LLM(RetryMixin, DebugMixin):
         Returns:
             bool: True if model is vision capable. Return False if model not supported by litellm.
         """
+
+        # Allow manual override via environment variable
+        if os.getenv('OPENHANDS_FORCE_VISION', '').lower() in (
+            '1',
+            'true',
+            'yes',
+            'on',
+        ):
+            return True
+
         # litellm.supports_vision currently returns False for 'openai/gpt-...' or 'anthropic/claude-...' (with prefixes)
         # but model_info will have the correct value for some reason.
         # we can go with it, but we will need to keep an eye if model_info is correct for Vertex or other providers