Define explicit open-source licensing and trademark boundaries

[ipicoinrepo]

Summary

• license community software and documentation under Apache-2.0
• dedicate IPI Improvement Proposals to CC0-1.0
• exclude preserved historical legal documents from blanket grants
• add a clear trademark and independent-fork policy
• enforce the licensing files in community validation

Verification

• Community standards validation passes
• Markdown links and patch whitespace were checked
• No repositories or historical documents were deleted