fix: stabilize opencode declarations across package managers

.opencode/tools/check-coverage.ts

@@ -5,11 +5,11 @@
  * Supports common coverage report formats.
  */
 
-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 checkCoverageTool: ToolDefinition = tool({
   description:
     "Check test coverage against a threshold and identify files with low coverage. Reads coverage reports from common locations.",
   args: {
@@ -100,6 +100,8 @@ export default tool({
   },
 })
 
+export default checkCoverageTool
+
 interface CoverageSummary {
   total: {
     lines: number