fix: rename build script to build:all to avoid arborist git dep preparation failure

opencode's bundled arborist triggers git dep preparation when it sees
build/prepare/prepack scripts, which fails due to invalid npm binary path.
Renaming to build:all avoids the trigger.

package.json

@@ -5,7 +5,7 @@
   "description": "OpenCode V2 plugin for Matrix messaging integration",
   "main": "dist/index.js",
   "scripts": {
-    "build": "tsc",
+    "build:all": "tsc",
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {