build(deps): bump @opencode-ai/plugin in /config/lib

Bumps @opencode-ai/plugin from 1.15.4 to 1.18.1.

---
updated-dependencies:
- dependency-name: "@opencode-ai/plugin"
  dependency-version: 1.18.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

config/lib/package.json

@@ -1,6 +1,6 @@
 {
 	"dependencies": {
-		"@opencode-ai/plugin": "1.15.4",
+		"@opencode-ai/plugin": "1.18.1",
 		"@types/bun": "1.3.11",
 		"@types/node": "25.5.0"
 	}