fix: eliminate panic/unwrap crash risks in apos consensus engine

Replace 1 panic!() and 30+ unwrap() calls in apos.rs with proper
Result error propagation and graceful error handling to prevent node
crashes from lock poisoning, cache misses, or missing header fields.

Also replace println!() with tracing::info!() in chainspec/spec.rs
and remove unused imports in network-api/block.rs.

Author: MiraWells

Cargo.lock

@@ -29,6 +29,7 @@ alloy-consensus.workspace = true
 auto_impl.workspace = true
 serde_json.workspace = true
 derive_more.workspace = true
+tracing.workspace = true
 
 [dev-dependencies]
 # eth

crates/chainspec/Cargo.toml

@@ -164,10 +164,7 @@ fn make_chain_spec(
     };
     spec.genesis.config.dao_fork_support = true;
     let state_root = state_root_ref_unhashed(&spec.genesis.alloc);
-    println!(
-        "Computed state_root from genesis alloc: state_root={}",
-        state_root
-    );
+    tracing::info!(target: "chainspec", %state_root, "Computed state_root from genesis alloc");
     spec.into()
 }