ReAct chain example created (#298)

* Added Java code into ts branch

* ReAct example added.

* Update react-chain.jsonnet

JS/edgechains/examples/react-chain/.gitignore

@@ -0,0 +1,8 @@
+# standard exclusions
+node_modules
+
+# build artifacts
+dist
+
+# environment files
+.env

JS/edgechains/examples/react-chain/README.md

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+## How to run ReActChain:-
+
+-   Use the following command in the root directory to run this example:
+
+    `npm i`
+
+    `npm run build`
+
+    `npm start`
+
+-   To use this example make a `POST` request call on `http://localhost:3000/react-chain`.
+-   Request body:
+    `{"prompt": "Your Search Topic"}`

JS/edgechains/examples/react-chain/esbuild.build.js

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+const esbuild = require("esbuild");
+const path = require("path");
+const fs = require("fs");
+const { execSync } = require("child_process");
+
+const outputDir = path.resolve(__dirname, "dist");
+
+if (!fs.existsSync(outputDir)) {
+    fs.mkdirSync(outputDir);
+}
+
+const distPath = path.join(process.cwd(), "dist");
+
+fs.promises.mkdir(distPath, { recursive: true });
+
+esbuild
+    .build({
+        entryPoints: ["./src/index.ts"],
+        bundle: true,
+        minify: true,
+        platform: "node",
+        outfile: "./dist/index.js",
+        tsconfig: "./tsconfig.json",
+        target: "node21.1.0",
+        external: [
+            "express",
+            "tsx",
+            "typescript",
+            "typeorm",
+            "react",
+            "react-dom",
+            "pg",
+            "jsdom",
+            "hono",
+            "@hanazuki/node-jsonnet",
+            "readline/promises",
+        ],
+        format: "cjs",
+        loader: {
+            ".html": "text",
+            ".css": "css",
+            ".jsonnet": "text",
+        },
+    })
+    .catch(() => process.exit(1));

JS/edgechains/examples/react-chain/ormconfig.json

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+{
+    "type": "postgres",
+    "host": "db.rmzqtepwnzoxgkkzjctt.supabase.co",
+    "port": 5432,
+    "username": "postgres",
+    "password": "xaX0MYcf1YiJlChK",
+    "database": "postgres",
+    "entities": ["dist/entities/**/*.js"],
+    "synchronize": false,
+    "logging": false
+}