fix: resolve all fmt and clippy warnings

Main lib (src/):
- Add #[allow(dead_code)] for build_info field (stored to prevent Prometheus unregistration)
- Add #[allow(dead_code)] for first_seen field (reserved for future rate limiting)
- Replace .or_insert_with(RelaySyncNeeds::default) with .or_default()
- Replace manual div_ceil implementations with .div_ceil(100)

Test code (tests/):
- Replace .expect(&format!(...)) with .unwrap_or_else(|_| panic!(...))
- Remove needless borrows in fetch_metrics() calls
- Add #[allow(dead_code)] and #[allow(unused_imports)] to test helpers module

grasp-audit:
- Apply cargo fmt to fix formatting

1 files changed, 7 insertions, 2 deletions

diff --git a/src/main.rs b/src/main.rs
index 97a14eb..6d8b4dd 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -37,7 +37,9 @@ async fn main() -> Result<()> {
     // Initialize metrics if enabled
     let metrics = if config.metrics_enabled {
         info!("Metrics enabled on /metrics endpoint");
-        Some(Arc::new(Metrics::new(config.metrics_connection_per_ip_abuse_threshold)))
+        Some(Arc::new(Metrics::new(
+            config.metrics_connection_per_ip_abuse_threshold,
+        )))
     } else {
         info!("Metrics disabled");
         None
@@ -65,7 +67,10 @@ async fn main() -> Result<()> {
         );
 
         if config.sync_bootstrap_relay_url.is_some() {
-            info!("Starting proactive sync with bootstrap relay: {:?}", config.sync_bootstrap_relay_url);
+            info!(
+                "Starting proactive sync with bootstrap relay: {:?}",
+                config.sync_bootstrap_relay_url
+            );
         } else {
             info!("Proactive sync enabled (will discover relays from stored announcements)");
         }