fix: handle array content and normalize tool_calls from providers

[efecnc]

Summary

• Fixes NoContent error when providers (Gemini, OpenRouter) return content as an array of parts instead of a plain string
• Fixes silent loss of tool_calls when arguments is returned as a JSON object instead of a JSON-encoded string (Gemini)
• Adds warn-level logging when tool_calls parsing fails instead of silently dropping

Root Cause

1. Array content: content_val.as_str() returns None for arrays → NoContent error → entire response (including tool_calls) is lost
2. Tool_calls parse: serde_json::from_value(...).ok() silently converts parse errors to None → model's tool call intent is completely lost → empty responses or re-prompt loops

Test plan

• Verify cargo check passes
• Test with Gemini via OpenAI-compatibility endpoint (returns array content)
• Test with DeepSeek / OpenAI (should continue working as before)
• Verify tool calls work across all providers

[gemini-code-assist]

Code Review

This pull request updates the LLMClient in src/utils.rs to improve compatibility with various LLM providers by handling content returned as an array of parts and normalizing tool call arguments from JSON objects or arrays into strings. Feedback suggests returning an error instead of an empty string when encountering unexpected content types to prevent silent failures and recommends using the warn! macro directly for consistency with the rest of the codebase.

[gemini-code-assist]

The catch-all else block now returns an empty string, which silently ignores malformed content (e.g., if the provider returns an object or a number). The previous implementation correctly errored out in these cases using LLMError::NoContent. It is better to preserve this error for truly unexpected types to help with debugging and ensure the response follows the expected schema.

Suggested change

	"".to_string()
	return Err(LLMError::NoContent);

[gemini-code-assist]

Use the imported warn! macro instead of the fully qualified log::warn! for consistency with how debug! and info! are used elsewhere in the file.

Suggested change

	log::warn!(
	warn!(

[efecnc]

✅ Fixes applied:

• Catch-all else now returns LLMError::NoContent instead of silently swallowing errors with empty string
• log::warn! replaced with imported warn! macro for consistency
• Array content parsing and tool_calls normalization preserved

Ready for re-review.