fix: stabilize opencode declarations across package managers

.opencode/tools/run-tests.ts

@@ -5,11 +5,11 @@
  * Automatically detects the package manager and test framework.
  */
 
-import { tool } from "@opencode-ai/plugin/tool"
+import { tool, type ToolDefinition } from "@opencode-ai/plugin/tool"
 import * as path from "path"
 import * as fs from "fs"
 
-export default tool({
+const runTestsTool: ToolDefinition = tool({
   description:
     "Run the test suite with optional coverage, watch mode, or specific test patterns. Automatically detects package manager (npm, pnpm, yarn, bun) and test framework.",
   args: {
@@ -97,6 +97,8 @@ export default tool({
   },
 })
 
+export default runTestsTool
+
 async function detectPackageManager(cwd: string): Promise<string> {
   const lockFiles: Record<string, string> = {
     "bun.lockb": "bun",