feat(config): add Zod schema validation and JSON Schema generation

- Add Zod schema for oh-my-opencode.json configuration validation
- Generate JSON Schema at build time for IDE autocompletion
- Add safeParse validation with error reporting on config load
- Export OhMyOpenCodeConfigSchema for programmatic usage
- Add build:schema script and ./schema.json export
- Update README with $schema usage documentation

script/build-schema.ts

@@ -0,0 +1,28 @@
+#!/usr/bin/env bun
+import * as z from "zod"
+import { OhMyOpenCodeConfigSchema } from "../src/config/schema"
+
+const SCHEMA_OUTPUT_PATH = "dist/oh-my-opencode.schema.json"
+
+async function main() {
+  console.log("Generating JSON Schema...")
+
+  const jsonSchema = z.toJSONSchema(OhMyOpenCodeConfigSchema, {
+    io: "input",
+    target: "draft-7",
+  })
+
+  const finalSchema = {
+    $schema: "http://json-schema.org/draft-07/schema#",
+    $id: "https://raw.githubusercontent.com/code-yeongyu/oh-my-opencode/master/dist/oh-my-opencode.schema.json",
+    title: "Oh My OpenCode Configuration",
+    description: "Configuration schema for oh-my-opencode plugin",
+    ...jsonSchema,
+  }
+
+  await Bun.write(SCHEMA_OUTPUT_PATH, JSON.stringify(finalSchema, null, 2))
+
+  console.log(`✓ JSON Schema generated: ${SCHEMA_OUTPUT_PATH}`)
+}
+
+main()