feat(lsp): add kotlin-ls LSP server support (#782)

Add Kotlin LSP server (kotlin-ls) to the built-in servers catalog,
syncing with OpenCode's server.ts. Includes:
- BUILTIN_SERVERS entry with kotlin-lsp command
- LSP_INSTALL_HINTS entry pointing to GitHub repo
- Extensions: .kt, .kts (already in EXT_TO_LANG)

Co-authored-by: justsisyphus <sisyphus-dev-ai@users.noreply.github.com>

src/tools/lsp/constants.ts

@@ -80,6 +80,7 @@ export const LSP_INSTALL_HINTS: Record<string, string> = {
   tinymist: "See https://github.com/Myriad-Dreamin/tinymist",
   "haskell-language-server": "ghcup install hls",
   bash: "npm install -g bash-language-server",
+  "kotlin-ls": "See https://github.com/Kotlin/kotlin-lsp",
 }
 
 // Synced with OpenCode's server.ts
@@ -246,6 +247,10 @@ export const BUILTIN_SERVERS: Record<string, Omit<LSPServerConfig, "id">> = {
     command: ["haskell-language-server-wrapper", "--lsp"],
     extensions: [".hs", ".lhs"],
   },
+  "kotlin-ls": {
+    command: ["kotlin-lsp"],
+    extensions: [".kt", ".kts"],
+  },
 }
 
 // Synced with OpenCode's language.ts