feat: add vision document for resource management

[scotwells]

Summary

This PR introduces a vision document for the Milo platform's resource management system. The document outlines both implemented features and planned capabilities for building a business-oriented resource management foundation that serves as the system of record for all business resources, enabling service providers to define, manage, and govern any type of business resource throughout its lifecycle.

Key Additions

• Core Vision: Establishes resource management as the system of record for business operations with hierarchical multi-tenancy, extensible resource types, and declarative APIs
• Current State: Documents implemented features including resource hierarchy, quota management, garbage collection, and native platform capabilities
• Planned Capabilities: Details future enhancements such as advanced search, lifecycle policies, resource bundles, knowledge graph foundation, and admission control
• Integration Architecture: Identifies key integration points with IAM, billing, service catalog, telemetry, and audit systems
• Use Cases: Covers resource management needs from individual developers to global enterprises

Context

The resource management system serves as the authoritative source of truth and foundation for the Milo business operating system, providing critical capabilities for:

• Service provider platforms requiring complex resource modeling
• Multi-tenant environments with hierarchical organization structures
• Business operations requiring governance, compliance, and lifecycle management
• Integration with existing business systems and workflows

[ecv]

feature branch merge! @scotwells do we want this

[mksinghtx]

LGTM