Fix unit test for startup batching behavior

Added `end_startup_mode()` method for tests to manually transition out of
startup batching mode. Updated `test_contract_caching_and_eviction` to call
this method before testing immediate announcements.

The test was failing because the new batching implementation returns `None`
during the 30-second startup grace period, but the test runs instantaneously
and expects immediate announcements.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: sanity

crates/core/src/node/proximity_cache.rs

@@ -151,6 +151,13 @@ impl ProximityCacheManager {
         }
     }
 
+    /// Manually end startup mode (for testing)
+    /// This allows tests to transition out of startup batching mode immediately
+    #[cfg(test)]
+    pub fn end_startup_mode(&self) {
+        self.startup_mode.store(false, Ordering::Relaxed);
+    }
+
     /// Flush batched announcements from startup period
     /// This should be called after the node's startup/initialization phase completes
     /// Returns a single announcement containing all contracts cached during startup
@@ -206,7 +213,9 @@ impl ProximityCacheManager {
             let op_manager = match op_manager.upgrade() {
                 Some(manager) => manager,
                 None => {
-                    debug!("PROXIMITY_PROPAGATION: OpManager dropped, skipping startup batch flush");
+                    debug!(
+                        "PROXIMITY_PROPAGATION: OpManager dropped, skipping startup batch flush"
+                    );
                     return;
                 }
             };
@@ -605,6 +614,9 @@ mod tests {
         let cache = ProximityCacheManager::new();
         let contract_key = create_test_contract_key();
 
+        // End startup mode to get immediate announcements in this test
+        cache.end_startup_mode();
+
         // Test caching a contract generates immediate announcement
         let announcement = cache.on_contract_cached(&contract_key).await;
         assert!(announcement.is_some());