fix: add json tags to DeployResult for camelCase serialization

DeployResult struct fields were serializing as PascalCase (Success,
Messages, Errors) but the TypeScript frontend expected camelCase
(success, messages, errors). Adding json:"..." tags fixes the mismatch.

internal/sshmanager/deploy.go

@@ -20,9 +20,9 @@ type DeployKey struct {
 }
 
 type DeployResult struct {
-	Success  bool
-	Messages []string
-	Errors   []string
+	Success  bool     `json:"success"`
+	Messages []string `json:"messages"`
+	Errors   []string `json:"errors"`
 }
 
 func DeployKeysToMachine(ctx context.Context, serverKeyPath string, host string, port int, user string, keys []DeployKey, knownHostsHosts []string) (*DeployResult, error) {