fix: normalize tool_args before validation in process_tools

[wgnrai]

Fix for #1512

Problem

validate_tool_request() crashes with ValueError when an LLM outputs "args" instead of "tool_args" in the tool request JSON.

Solution

Add normalization before calling validate_tool_request():

• Map "args" → "tool_args" if "tool_args" is missing
• Default "tool_args" to empty dict if not a dict type

Changes

• agent.py: Added 4-line normalization block before validate_tool_request() call in process_tools()

Testing

• Handles {"tool_name": "x", "args": {}} → normalizes to {"tool_name": "x", "tool_args": {}}
• Correctly formatted requests pass unchanged
• Non-dict values defaulted to {}

Closes #1512