fix: harden typed metrics review findings

crates/crank-metrics/src/bin/crank-metrics-contract.rs

@@ -1,6 +1,6 @@
-use std::{fs, process::ExitCode};
+use std::process::ExitCode;
 
-const SNAPSHOT: &str = "docs/schemas/metrics-registry-v1.json";
+const SNAPSHOT: &str = include_str!("../../../../docs/schemas/metrics-registry-v1.json");
 
 fn main() -> ExitCode {
     let rendered = match crank_metrics::render_metric_schema_json() {
@@ -19,18 +19,14 @@ fn main() -> ExitCode {
         eprintln!("metrics_contract_invalid_command");
         return ExitCode::FAILURE;
     }
-    match fs::read_to_string(SNAPSHOT) {
-        Ok(snapshot) if snapshot == rendered => {
+    match SNAPSHOT {
+        snapshot if snapshot == rendered => {
             println!("metrics_contract_ok schema_version=1");
             ExitCode::SUCCESS
         }
-        Ok(_) => {
+        _ => {
             eprintln!("metrics_contract_drift");
             ExitCode::FAILURE
         }
-        Err(_) => {
-            eprintln!("metrics_contract_missing");
-            ExitCode::FAILURE
-        }
     }
 }