chore(deps-dev): keep one @opencode-ai/sdk copy in the tree

@opencode-ai/plugin depends on an exact sdk version while the root devDependency floats, so npm nested a second copy and the two OpencodeClient types stopped being assignable (TS2322 at src/plugin/index.ts:177). An override pinned to the root devDependency collapses them to one version; the devDependency range then tracks the plugin's pin without re-nesting.

Author: justin-carper

package-lock.json

@@ -63,6 +63,7 @@
     "semver": "^7.8.4"
   },
   "overrides": {
+    "@opencode-ai/sdk": "$@opencode-ai/sdk",
     "undici": "^6.28.0",
     "tar": "^7.5.11",
     "node-gyp": "^12.4.0",
@@ -73,8 +74,8 @@
   },
   "devDependencies": {
     "@ai-sdk/provider": "^3.0.15",
-    "@opencode-ai/sdk": "^1.18.21",
-    "@types/node": "^26.2.0",
+    "@opencode-ai/sdk": "^1.18.30",
+    "@types/node": "^26.4.1",
     "@types/semver": "^7.8.0",
     "tsup": "^8.5.1",
     "typescript": "^6.0.3",