docs: Overhaul README for spec-repository positioning

[kernel-gd]

Summary

• Replaces the entire product/marketing README with a spec-repository README aligned to GenOps v0.1
• Removes: SDK Quick Start, Python code examples, 50+ integration lists, dashboard mockups, badge shields, persona sections, trademark/legal boilerplate, promotional CTAs
• Adds: What GenOps Is, Why This Exists, Design Principles, Relationship to OpenTelemetry, Compliance, What GenOps Does Not Define, Versioning, Repository Structure, Contributing, Status, License
• Net reduction: 439 lines removed, 83 lines added

Test plan

• Verify no vendor references, no SDK/implementation content, no marketing language
• Verify all links resolve (spec file, LICENSE)
• Verify tone reads as standards-grade, CNCF-legible

🤖 Generated with Claude Code

[github-actions]

❌ DCO Check Failed

Your commits are missing the required "Signed-off-by" line.

How to fix this:

1. For new commits, use the -s flag:

   git commit -s -m "Your commit message"

2. To fix existing commits in your PR:

   # For the last commit
   git commit --amend --signoff
   
   # For multiple commits (replace N with number of commits)
   git rebase --signoff HEAD~N
   
   # Force push the updated commits
   git push --force-with-lease

What is DCO?

The Developer Certificate of Origin (DCO) is a legally lightweight way for contributors to confirm they have the right to submit code to the project.

By signing off, you certify that:

• You wrote the code or have the right to submit it
• You agree to the project's license terms
• Your contribution follows the Developer Certificate of Origin

Need help?

Check our Contributing Guide or ask questions in this PR!