Add prompt-gateway: MCP-based task contract compiler and agent router

prompt-gateway/.gitignore

@@ -0,0 +1,8 @@
+node_modules/
+dist/
+bin/agent
+bin/prompt-gateway
+.prompt-gateway/
+*.db
+*.db-wal
+*.db-shm

prompt-gateway/esbuild.config.mjs

@@ -0,0 +1,39 @@
+import * as esbuild from "esbuild";
+
+const shared = {
+  bundle: true,
+  platform: "node",
+  target: "node20",
+  format: "esm",
+  sourcemap: true,
+  // better-sqlite3 is a native addon — must stay external
+  external: ["better-sqlite3"],
+  banner: {
+    // ESM needs createRequire for native modules
+    js: `
+import { createRequire } from 'module';
+import { fileURLToPath } from 'url';
+import { dirname } from 'path';
+const require = createRequire(import.meta.url);
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+`.trim(),
+  },
+};
+
+// CLI: agent command
+await esbuild.build({
+  ...shared,
+  entryPoints: ["src/bin/agent.ts"],
+  outfile: "dist/agent.mjs",
+});
+
+// Daemon: prompt-gateway server
+await esbuild.build({
+  ...shared,
+  entryPoints: ["src/index.ts"],
+  outfile: "dist/prompt-gateway.mjs",
+});
+
+console.log("✓ Built dist/agent.mjs");
+console.log("✓ Built dist/prompt-gateway.mjs");