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.

crates/teepot/src/quote/tcblevel.rs

@@ -14,7 +14,9 @@ use std::{
 pub use enumset::EnumSet;
 
 /// TCB level
-#[derive(EnumSetType, Debug)]
+#[derive(EnumSetType, Debug, Serialize, Deserialize)]
+#[enumset(serialize_repr = "list")]
+#[non_exhaustive]
 pub enum TcbLevel {
     /// TCB is up to date
     Ok,