cli-17: Fix special character escaping in tool descriptions

[szmania]

Summary

This PR fixes special character escaping issues in tool descriptions across multiple files:

• Fixed improper line breaks and spacing in tool description strings
• Added proper JSON escaping for special characters in tool descriptions (particularly in models.py)
• Improved consistency in multi-line string formatting

Changes

The changes primarily focus on:

1. models.py: Added JSON escaping for tool descriptions to handle special characters like quotes, backslashes, and newlines properly. This prevents JSON parsing errors when these descriptions are passed to LLM APIs.

2. agent_coder.py, io.py, context_manager.py, read_range.py: Fixed inconsistent line breaks and spacing in multi-line strings to improve readability and maintain consistency.

3. tests/basic/test_models.py: Added a test case to verify that tool descriptions with special characters are properly escaped before being sent to the LLM API.

Why This Matters

These changes ensure that:

• Tool descriptions with special characters (quotes, backslashes, newlines) are properly escaped when sent to LLM APIs
• The codebase maintains consistent formatting for multi-line strings
• We prevent potential JSON parsing errors that could occur when tool descriptions contain special characters

The test case verifies that the escaping mechanism works correctly with complex strings containing various special characters.

Testing

The changes have been tested with the new test case in test_models.py that verifies the escaping of special characters in tool descriptions.

Fixes: cli-17