chore: import upstream snapshot with attribution

@omniroute/opencode-plugin/tsup.config.ts

@@ -0,0 +1,20 @@
+import { defineConfig } from "tsup";
+
+export default defineConfig({
+  entry: ["src/index.ts"],
+  format: ["esm"],
+  dts: true,
+  clean: true,
+  sourcemap: false,
+  splitting: false,
+  treeshake: false,
+  target: "node22",
+  outDir: "dist",
+  minify: false,
+  cjsInterop: false,
+  // Bundle runtime deps so the .tgz / npm install is self-contained.
+  // `zod` is required at runtime by the options schema and would otherwise
+  // need a peer install when the plugin is loaded directly from a file path
+  // in opencode.jsonc.
+  noExternal: ["zod"],
+});