Add Production Dependency Validation

[transientlunatic]

Summary: Validate that productions in needs will provide required data products before submission.

Description:

Add validate_needs() method to Analysis class that:

• Checks if productions listed in needs provide the required inputs (we can find this via the enhancements described in Add Pipeline Input/Output Metadata System #94)
• Warns (or errors) if required data products won't be available
• Runs at build/submission time, not runtime

Example validation:

def validate_needs(self):
    required = self.pipeline.get_actual_inputs(self)
    for requirement in required:
        satisfied = any(
            requirement in dep.pipeline.get_actual_outputs(dep)
            for dep in self.needs
        )
        if not satisfied:
            warnings.warn(f"Production requires '{requirement}' but no dependency provides it")

Benefits:

• Catch configuration errors before wasting compute time
• Better user feedback about missing dependencies
• Foundation for smarter workflow orchestration