Revert "Add oh-my-opencode-slim (#1100)"

This PR was incorrectly merged by AI agent without proper project owner review.

The AI evaluated this as 'ULTRA SAFE' because it only modified README files,
but failed to recognize that adding external fork promotions to the project
README requires explicit project owner approval - not just technical safety.

This reverts commit 912a56db85.

README.md

@@ -39,11 +39,6 @@
 
 > This is coding on steroids—`oh-my-opencode` in action. Run background agents, call specialized agents like oracle, librarian, and frontend engineer. Use crafted LSP/AST tools, curated MCPs, and a full Claude Code compatibility layer.
 
-> [!TIP]
-> **Looking for a lighter version?**
->
-> Check out [oh-my-opencode-slim](https://github.com/alvinunreal/oh-my-opencode-slim) - a streamlined fork with essential features for those who prefer a minimal setup.
-
 # Claude OAuth Access Notice
 
 ## TL;DR