Add RQLite join address connectivity testing

- Test join address reachability before attempting to join cluster
- Fall back to starting new cluster if join address is unreachable
- Add comprehensive logging for join address testing
- Prevent RQLite fatal errors when bootstrap node is down

This fixes the issue where secondary nodes fail with 'invalid join address'
when the primary bootstrap node is not accessible on port 4001.

pkg/database/rqlite.go

@@ -69,7 +69,15 @@ func (r *RQLiteManager) Start(ctx context.Context) error {
 		
 		// Validate join address format before using it
 		if strings.HasPrefix(r.config.RQLiteJoinAddress, "http://") {
+			// Test if the join address is reachable before attempting to join
+			if err := r.testJoinAddress(r.config.RQLiteJoinAddress); err != nil {
+				r.logger.Warn("Join address is not reachable, starting as new cluster instead",
+					zap.String("join_address", r.config.RQLiteJoinAddress),
+					zap.Error(err))
+				// Don't add the -join parameter, let this node start its own cluster
+			} else {
 				args = append(args, "-join", r.config.RQLiteJoinAddress)
+			}
 		} else {
 			r.logger.Warn("Invalid join address format, skipping join", zap.String("address", r.config.RQLiteJoinAddress))
 			return fmt.Errorf("invalid RQLite join address format: %s (must start with http://)", r.config.RQLiteJoinAddress)
@@ -289,3 +297,26 @@ func (r *RQLiteManager) getExternalIP() (string, error) {
 
 	return "", fmt.Errorf("no suitable IP address found")
 }
+
+// testJoinAddress tests if a join address is reachable
+func (r *RQLiteManager) testJoinAddress(joinAddress string) error {
+	// Test connection to the join address with a short timeout
+	client := &http.Client{Timeout: 5 * time.Second}
+	
+	// Try to connect to the status endpoint
+	statusURL := joinAddress + "/status"
+	r.logger.Debug("Testing join address", zap.String("url", statusURL))
+	
+	resp, err := client.Get(statusURL)
+	if err != nil {
+		return fmt.Errorf("failed to connect to join address %s: %w", joinAddress, err)
+	}
+	defer resp.Body.Close()
+	
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("join address %s returned status %d", joinAddress, resp.StatusCode)
+	}
+	
+	r.logger.Info("Join address is reachable", zap.String("address", joinAddress))
+	return nil
+}