feat: Support compound duration parsing in Duration.parse()

[dyleeeeeeee]

Description

Enhances Duration.parse() to support compound duration strings like "1h30m", "2d3h15m", etc.

Motivation

Currently, Duration.parse() only supports single-unit durations ("2h", "30m").
This limitation requires users to convert compound durations manually. For example,
"1 hour and 30 minutes" cannot be expressed as "1h30m" and must be converted to "90m".

Changes

• Modified Duration.parse() to use regex pattern matching for flexible parsing
• Supports multiple units in a single string: "1h30m", "2d3h15m30s", etc.
• Maintains full backward compatibility with existing single-unit durations
• Added comprehensive test coverage for new functionality

Testing

• All existing tests pass
• Added new tests covering compound duration parsing
• Verified backward compatibility with single-unit durations

Examples

# New functionality
Duration.parse("1h30m")      # 90 minutes
Duration.parse("2d3h15m")    # 2 days, 3 hours, 15 minutes
Duration.parse("1h30m45s")   # 1 hour, 30 minutes, 45 seconds

# Existing functionality (still works)
Duration.parse("2h")         # 2 hours
Duration.parse("45m")        # 45 minutes

[martinschaer]

hi @dyleeeeeeee ! Can you run uv run ruff format src/ and uv run ruff check --fix src/ to fix the "CI / Check format" error?