refactor: move brother_node development artifact to dev/test-nodes subdirectory

Development Artifact Cleanup:
✅ BROTHER_NODE REORGANIZATION: Moved development test node to appropriate location
- dev/test-nodes/brother_node/: Moved from root directory for better organization
- Contains development configuration, test logs, and test chain data
- No impact on production systems - purely development/testing artifact

✅ DEVELOPMENT ARTIFACTS IDENTIFIED:
- Chain ID: aitbc-brother-chain (test/development chain)
- Ports: 8010 (P2P) and 8011 (RPC) - different from production
- Environment: .env file with test configuration
- Logs: rpc.log and node.log from development testing session (March 15, 2026)

✅ ROOT DIRECTORY CLEANUP: Removed development clutter from production directory
- brother_node/ moved to dev/test-nodes/brother_node/
- Root directory now contains only production-ready components
- Development artifacts properly organized in dev/ subdirectory

DIRECTORY STRUCTURE IMPROVEMENT:
📁 dev/test-nodes/: Development and testing node configurations
🏗️ Root Directory: Clean production structure with only essential components
🧪 Development Isolation: Test environments separated from production

BENEFITS:
✅ Clean Production Directory: No development artifacts in root
✅ Better Organization: Development nodes grouped in dev/ subdirectory
✅ Clear Separation: Production vs development environments clearly distinguished
✅ Maintainability: Easier to identify and manage development components

RESULT: Successfully moved brother_node development artifact to dev/test-nodes/ subdirectory, cleaning up the root directory while preserving development testing environment for future use.

dev/env/node_modules/ethers/src.ts/providers/provider-chainstack.ts

@@ -0,0 +1,113 @@
+/**
+ *  [[link-chainstack]] provides a third-party service for connecting to
+ *  various blockchains over JSON-RPC.
+ *
+ *  **Supported Networks**
+ *
+ *  - Ethereum Mainnet (``mainnet``)
+ *  - Arbitrum (``arbitrum``)
+ *  - BNB Smart Chain Mainnet (``bnb``)
+ *  - Polygon (``matic``)
+ *
+ *  @_subsection: api/providers/thirdparty:Chainstack  [providers-chainstack]
+ */
+import {
+    defineProperties, FetchRequest, assertArgument
+} from "../utils/index.js";
+
+import { showThrottleMessage } from "./community.js";
+import { Network } from "./network.js";
+import { JsonRpcProvider } from "./provider-jsonrpc.js";
+
+import type { AbstractProvider } from "./abstract-provider.js";
+import type { CommunityResourcable } from "./community.js";
+import type { Networkish } from "./network.js";
+
+
+function getApiKey(name: string): string {
+    switch (name) {
+        case "mainnet": return "39f1d67cedf8b7831010a665328c9197";
+        case "arbitrum": return "0550c209db33c3abf4cc927e1e18cea1"
+        case "bnb": return "98b5a77e531614387366f6fc5da097f8";
+        case "matic": return "cd9d4d70377471aa7c142ec4a4205249";
+    }
+
+    assertArgument(false, "unsupported network", "network", name);
+}
+
+function getHost(name: string): string {
+    switch(name) {
+        case "mainnet":
+            return "ethereum-mainnet.core.chainstack.com";
+        case "arbitrum":
+            return "arbitrum-mainnet.core.chainstack.com";
+        case "bnb":
+            return "bsc-mainnet.core.chainstack.com";
+        case "matic":
+            return "polygon-mainnet.core.chainstack.com";
+    }
+
+    assertArgument(false, "unsupported network", "network", name);
+}
+
+/**
+ *  The **ChainstackProvider** connects to the [[link-chainstack]]
+ *  JSON-RPC end-points.
+ *
+ *  By default, a highly-throttled API key is used, which is
+ *  appropriate for quick prototypes and simple scripts. To
+ *  gain access to an increased rate-limit, it is highly
+ *  recommended to [sign up here](link-chainstack).
+ */
+export class ChainstackProvider extends JsonRpcProvider implements CommunityResourcable {
+    /**
+     *  The API key for the Chainstack connection.
+     */
+    readonly apiKey!: string;
+
+    /**
+     *  Creates a new **ChainstackProvider**.
+     */
+    constructor(_network?: Networkish, apiKey?: null | string) {
+        if (_network == null) { _network = "mainnet"; }
+        const network = Network.from(_network);
+
+        if (apiKey == null) { apiKey = getApiKey(network.name); }
+
+        const request = ChainstackProvider.getRequest(network, apiKey);
+        super(request, network, { staticNetwork: network });
+
+        defineProperties<ChainstackProvider>(this, { apiKey });
+    }
+
+    _getProvider(chainId: number): AbstractProvider {
+        try {
+            return new ChainstackProvider(chainId, this.apiKey);
+        } catch (error) { }
+        return super._getProvider(chainId);
+    }
+
+    isCommunityResource(): boolean {
+        return (this.apiKey === getApiKey(this._network.name));
+    }
+
+    /**
+     *  Returns a prepared request for connecting to %%network%%
+     *  with %%apiKey%% and %%projectSecret%%.
+     */
+    static getRequest(network: Network, apiKey?: null | string): FetchRequest {
+        if (apiKey == null) { apiKey = getApiKey(network.name); }
+
+        const request = new FetchRequest(`https:/\/${ getHost(network.name) }/${ apiKey }`);
+        request.allowGzip = true;
+
+        if (apiKey === getApiKey(network.name)) {
+            request.retryFunc = async (request, response, attempt) => {
+                showThrottleMessage("ChainstackProvider");
+                return true;
+            };
+        }
+
+        return request;
+    }
+}