Add Kotlin LSP plugin for code intelligence

- Add kotlin-lsp entry to marketplace.json with support for .kt and .kts files
- Create README with installation instructions (brew install kotlin-lsp)
- Configure LSP server to use --stdio mode with 120s startup timeout

plugins/kotlin-lsp/README.md

@@ -0,0 +1,16 @@
+Kotlin language server for Claude Code, providing code intelligence, refactoring, and analysis.
+
+## Supported Extensions
+`.kt`
+`.kts`
+
+## Installation
+
+Install the Kotlin LSP CLI.
+
+```bash
+brew install JetBrains/utils/kotlin-lsp
+```
+
+## More Information
+- [kotlin LSP](https://github.com/Kotlin/kotlin-lsp)