Refactor LSP tools and add hover functionality

- Split diagnostics tool into separate lsp-diagnostics.ts file
- Add new lsp-hover.ts tool for LSP hover information
- Update tool exports and session integration
- Remove old diagnostics.ts file

🤖 Generated with opencode
Co-Authored-By: opencode <noreply@opencode.ai>

js/src/tool/index.ts

@@ -5,4 +5,5 @@ export * from "./glob";
 export * from "./grep";
 export * from "./view";
 export * from "./ls";
-export * from "./diagnostics";
+export * from "./lsp-diagnostics";
+export * from "./lsp-hover";