Add JSON minify/compact operation

[krisarmstrong]

Description

Add ability to minify/compact JSON by removing whitespace.

Tasks

• Add --minify flag to json_ops.py
• Ensure no trailing whitespace
• Add tests
• Update documentation

Example Usage

json-tools --minify -i formatted.json -o compact.json

Implementation

Use json.dumps(data, separators=(',', ':')) for compact output.

Success Criteria

• Produces valid, minimal JSON
• Preserves data integrity
• Works with large files