fix(security): validate project and service names to prevent path traversal

internal/scaffold/add.go

@@ -12,6 +12,10 @@ func Add(svcType, svcName string) error {
 		return fmt.Errorf("quikdb.yaml not found. Are you in a quikdb-frame project?")
 	}
 
+	if err := validateName(svcName, "service name"); err != nil {
+		return err
+	}
+
 	fullName := svcType + "-" + svcName
 	if svcType == "web" {
 		fullName = "web-" + svcName

internal/scaffold/init.go

@@ -7,6 +7,10 @@ import (
 )
 
 func Init(name, dbType string) error {
+	if err := validateName(name, "project name"); err != nil {
+		return err
+	}
+
 	if _, err := os.Stat(name); err == nil {
 		return fmt.Errorf("directory %s already exists", name)
 	}

internal/scaffold/validate.go

@@ -0,0 +1,18 @@
+package scaffold
+
+import (
+	"fmt"
+	"regexp"
+)
+
+// validName allows letters, numbers, hyphens, underscores.
+// Must start with a letter or number. Max 50 chars.
+// Rejects path traversal attempts like ../../etc or /absolute/path.
+var validName = regexp.MustCompile(`^[a-zA-Z0-9][a-zA-Z0-9_-]{0,49}$`)
+
+func validateName(name, label string) error {
+	if !validName.MatchString(name) {
+		return fmt.Errorf("invalid %s %q: use letters, numbers, hyphens, and underscores only (no slashes or dots)", label, name)
+	}
+	return nil
+}