refactor(verify-era-proof-attestation): modularize and restructure proof verification logic

- Split `verify-era-proof-attestation` into modular subcomponents for maintainability.
- Moved client, proof handling, and core types into dedicated modules.

bin/verify-era-proof-attestation/src/client/http.rs

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright (c) 2023-2025 Matter Labs
+
+//! HTTP client for making requests to external services
+
+use reqwest::Client;
+use serde::{de::DeserializeOwned, Serialize};
+use std::time::Duration;
+use url::Url;
+
+use crate::{
+    core::DEFAULT_HTTP_REQUEST_TIMEOUT,
+    error::{Error, Result},
+};
+
+/// Client for making HTTP requests
+#[derive(Clone)]
+pub struct HttpClient {
+    client: Client,
+}
+
+impl HttpClient {
+    /// Create a new HTTP client with default configuration
+    pub fn new() -> Self {
+        let client = Client::builder()
+            .timeout(Duration::from_secs(DEFAULT_HTTP_REQUEST_TIMEOUT))
+            .build()
+            .expect("Failed to create HTTP client");
+
+        Self { client }
+    }
+
+    /// Make a POST request to the specified URL with the provided body
+    pub async fn post<T: Serialize>(&self, url: &Url, body: T) -> Result<String> {
+        let response = self.client.post(url.clone()).json(&body).send().await?;
+        self.handle_response(response).await
+    }
+
+    /// Send a JSON request and parse the response
+    pub async fn send_json<T: Serialize, R: DeserializeOwned>(
+        &self,
+        url: &Url,
+        body: T,
+    ) -> Result<R> {
+        let response_text = self.post(url, body).await?;
+        let response: R = serde_json::from_str(&response_text)
+            .map_err(|e| Error::JsonRpcInvalidResponse(e.to_string()))?;
+
+        Ok(response)
+    }
+
+    /// Handle the HTTP response
+    async fn handle_response(&self, response: reqwest::Response) -> Result<String> {
+        let status = response.status();
+        let body = response.text().await?;
+
+        if status.is_success() {
+            Ok(body)
+        } else {
+            Err(Error::Http {
+                status_code: status.as_u16(),
+                message: body,
+            })
+        }
+    }
+}