fix: update bootstrap service and routes for cluster authentication

- Updated bootstrap service to use authenticated HTTP client with cluster auth headers
- Made GET /members/ endpoint unprotected for monitoring/inspection purposes
- All other cluster communication endpoints remain protected by cluster auth middleware

This ensures proper cluster formation while maintaining security for inter-node communication.

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

Co-Authored-By: Claude <noreply@anthropic.com>

integration_test.sh

@@ -124,7 +124,10 @@ EOF
 # Test 3: Cluster formation
 test_cluster_formation() {
     test_start "2-node cluster formation and Merkle Tree replication"
-    
+
+    # Shared cluster secret for authentication (Issue #13)
+    local CLUSTER_SECRET="test-cluster-secret-12345678901234567890"
+
     # Node 1 config
     cat > cluster1.yaml <<EOF
 node_id: "cluster-1"
@@ -138,8 +141,9 @@ gossip_interval_max: 10
 sync_interval: 10
 allow_anonymous_read: true
 allow_anonymous_write: true
+cluster_secret: "$CLUSTER_SECRET"
 EOF
-    
+
     # Node 2 config
     cat > cluster2.yaml <<EOF
 node_id: "cluster-2"
@@ -153,6 +157,7 @@ gossip_interval_max: 10
 sync_interval: 10
 allow_anonymous_read: true
 allow_anonymous_write: true
+cluster_secret: "$CLUSTER_SECRET"
 EOF
     
     # Start nodes
@@ -230,15 +235,18 @@ EOF
 # but same path. The Merkle tree sync should then trigger conflict resolution.
 test_conflict_resolution() {
     test_start "Conflict resolution test (Merkle Tree based)"
-    
+
     # Create conflicting data using our utility
     rm -rf conflict1_data conflict2_data 2>/dev/null || true
     mkdir -p conflict1_data conflict2_data
-    
+
     cd "$SCRIPT_DIR"
     if go run test_conflict.go "$TEST_DIR/conflict1_data" "$TEST_DIR/conflict2_data"; then
         cd "$TEST_DIR"
-        
+
+        # Shared cluster secret for authentication (Issue #13)
+        local CLUSTER_SECRET="conflict-cluster-secret-1234567890123"
+
         # Create configs
         cat > conflict1.yaml <<EOF
 node_id: "conflict-1"
@@ -250,8 +258,9 @@ log_level: "info"
 sync_interval: 3
 allow_anonymous_read: true
 allow_anonymous_write: true
+cluster_secret: "$CLUSTER_SECRET"
 EOF
-        
+
         cat > conflict2.yaml <<EOF
 node_id: "conflict-2"
 bind_address: "127.0.0.1"
@@ -262,6 +271,7 @@ log_level: "info"
 sync_interval: 3
 allow_anonymous_read: true
 allow_anonymous_write: true
+cluster_secret: "$CLUSTER_SECRET"
 EOF
         
         # Start nodes