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/verification/attestation.rs

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright (c) 2023-2025 Matter Labs
+
+use teepot::quote::{
+    error::QuoteContext, tee_qv_get_collateral, verify_quote_with_collateral,
+    QuoteVerificationResult,
+};
+
+use crate::error;
+
+/// Handles verification of attestation quotes
+pub struct AttestationVerifier;
+
+impl AttestationVerifier {
+    /// Verify an attestation quote
+    pub fn verify_quote(attestation_quote_bytes: &[u8]) -> error::Result<QuoteVerificationResult> {
+        // Get collateral for the quote
+        let collateral = QuoteContext::context(
+            tee_qv_get_collateral(attestation_quote_bytes),
+            "Failed to get collateral!",
+        )?;
+
+        // Get current time for verification
+        let unix_time: i64 = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .map_err(|e| error::Error::internal(format!("Failed to get system time: {}", e)))?
+            .as_secs() as _;
+
+        // Verify the quote with the collateral
+        let res =
+            verify_quote_with_collateral(attestation_quote_bytes, Some(&collateral), unix_time)?;
+
+        Ok(res)
+    }
+}