feat: add JS sdk (#1)

* feat: add JS sdk

* feat: add js sdk

Author: anyxem

docs/javascript-sdk/_category_.json

@@ -0,0 +1,7 @@
+{
+  "label": "JavaScript SDK",
+  "position": 4,
+  "link": {
+    "type": "generated-index"
+  }
+}

docs/javascript-sdk/getting-started.md

@@ -0,0 +1,28 @@
+---
+id: sdk-client
+title: Mintlayer SDK Client
+sidebar_label: SDK Client
+---
+
+# Mintlayer SDK Client
+
+The Mintlayer SDK provides a `Client` class that offers a high-level interface for interacting with the Mojito wallet extension.
+
+> 🧩 This SDK is meant to be used inside decentralized applications (dApps) that want to integrate Mintlayer features like sending transactions, minting tokens, issuing NFTs, staking, and more.
+
+---
+
+## Installation
+
+```bash
+npm install @mintlayer/sdk
+```
+
+## Getting Started
+
+```ts
+import { Client } from '@mintlayer/sdk';
+
+const client = await Client.create({ network: 'testnet' });
+```
+