feat: Add VastAI client

- Add a new VastAI client to the project.
- This client allows users to search for and create GPU instances on VastAI.
- It uses the VastAI API to interact with the platform.
- Includes functionality for searching offers, getting top offers, and creating instances.

Co-authored-by: mahmmoud.hassanein <mahmmoud.hassanein@gmail.com>

examples/develop/vastai/vastai_example.vsh

@@ -0,0 +1,24 @@
+#!/usr/bin/env -S v -n -w -gc none -no-retry-compilation -cc tcc -d use_openssl -enable-globals run
+
+import freeflowuniverse.herolib.clients.vastai
+import json
+import x.json2
+
+// Create client with direct API key
+// This uses VASTAI_API_KEY from environment
+mut va := vastai.get()!
+
+offers := va.search_offers()!
+println('offers: ${offers}')
+
+top_offers := va.get_top_offers(5)!
+println('top offers: ${top_offers}')
+
+create_instance_res := va.create_instance(
+	id:     top_offers[0].id
+	config: vastai.CreateInstanceConfig{
+		image: 'pytorch/pytorch:2.5.1-cuda12.4-cudnn9-runtime'
+		disk:  10
+	}
+)!
+println('create instance res: ${create_instance_res}')