Add machine-readable error codes for programmatic handling

[kyamagu]

Add error codes to resource limit exceptions for better programmatic handling:

class ResourceLimitError(ValueError):
    def __init__(self, message: str, error_code: str, limit_type: str, actual: int, limit: int):
        self.error_code = error_code  # e.g., "FILE_SIZE_EXCEEDED"
        self.limit_type = limit_type  # e.g., "max_file_size"
        self.actual = actual
        self.limit = limit
        super().__init__(message)

Benefits

• Easier to catch specific errors
• Better for API users and tools
• Enables automated retry with adjusted limits

Example Usage

try:
    convert("large.psd", "output.svg")
except ResourceLimitError as e:
    if e.error_code == "FILE_SIZE_EXCEEDED":
        # Retry with larger limit
        limits = ResourceLimits(max_file_size=e.actual + 100_000_000)
        convert("large.psd", "output.svg", resource_limits=limits)

Considerations

• Breaking change (new exception type)
• Need comprehensive error code taxonomy
• Should maintain backward compatibility with ValueError/TimeoutError
• Consider using exception groups for multiple violations