fix: pass model and llm_provider to ContextWindowExceededError constructor

[paulxg12]

What

Fix a TypeError in _call_llm_streaming and _call_llm_non_streaming that prevents context compaction from triggering when the LLM responds with a context overflow error.

Why

Fixes #270. When litellm raises a BadRequestError (or similar) indicating the prompt exceeds the model context window, the exception handlers attempt to re-raise it as ContextWindowExceededError but omit the required model and llm_provider positional arguments:

TypeError: ContextWindowExceededError.__init__() missing 2 required positional arguments: 'model' and 'llm_provider'

This prevents the except ContextWindowExceededError: handler in the main agent loop (line ~1692) from ever catching the error, so context compaction never fires. The session is permanently stuck throwing the same TypeError on every iteration.

How

Both _call_llm_streaming (line ~876) and _call_llm_non_streaming (line ~1033) now pass:

• model — from llm_params.get("model", "")
• llm_provider — extracted as the prefix before / in the model string (e.g. "openai", "anthropic", "bedrock")

These values are already available in llm_params at the call site.

Testing

• The fix is a minimal change (2 call sites, +10 lines) that matches the constructor signature used everywhere else in litellm.
• The except ContextWindowExceededError: handler in run_agent at line ~1692 can now correctly catch the re-raised error and trigger context compaction.

Checklist

• Follows existing code style
• No breaking changes
• Documentation updated if needed