refactor(schema): extract shared public schemas (#33571)

packages/schema/package.json

@@ -0,0 +1,22 @@
+{
+  "$schema": "https://json.schemastore.org/package.json",
+  "name": "@opencode-ai/schema",
+  "private": true,
+  "type": "module",
+  "license": "MIT",
+  "exports": {
+    ".": "./src/index.ts",
+    "./*": "./src/*.ts"
+  },
+  "scripts": {
+    "typecheck": "tsgo --noEmit"
+  },
+  "dependencies": {
+    "effect": "catalog:"
+  },
+  "devDependencies": {
+    "@tsconfig/bun": "catalog:",
+    "@types/bun": "catalog:",
+    "@typescript/native-preview": "catalog:"
+  }
+}