Additional doc improvements

[halcwb]

This pull request updates documentation across multiple files to improve clarity, ensure consistency, and establish canonical sources for toolchain requirements and disclaimers. The main themes are: consolidating environment variable and toolchain documentation, clarifying clinical and support disclaimers, and improving cross-referencing between documents.

Documentation consolidation and cross-referencing:

• Updated DEVELOPMENT.md, README.md, WARP.md, and architecture/design docs to establish the Toolchain Requirements section in DEVELOPMENT.md as the canonical source for supported .NET SDK, Node.js, and npm versions, and replaced or referenced this section from other docs. [1] [2] [3] [4] [5] [6]
• Consolidated environment variable setup instructions, referencing DEVELOPMENT.md#environment-configuration from README.md, WARP.md, and other docs, to avoid duplication and ensure consistency. [1] [2] [3]

Clinical and support disclaimers:

• Clarified and centralized the clinical use and support disclaimers, moving the canonical disclaimer to the Medical Advice Disclaimer section in SUPPORT.md, and referencing it from README.md and elsewhere. [1] [2] [3]
• Updated wording throughout to emphasize GenPRES is not for direct clinical use without validation and does not provide professional support services. [1] [2] [3]

Governance and maintainers:

• Added cross-references between GOVERNANCE.md and MAINTAINERS.md to clarify role definitions and the process for becoming a maintainer. [1] [2] [3]

Miscellaneous improvements:

• Improved the ARCHITECTURE.md file to serve as a stable index/landing page for deeper architecture documentation.
• Added a more detailed description to data/cache/README.md about cache data handling and repository policy.
• Minor updates to demo environment variable values and formatting for clarity in DEVELOPMENT.md.
• Updated last modified date in SUPPORT.md for accuracy.