feat: implement base template support

internal/template/base_templates.go

@@ -0,0 +1,34 @@
+package template
+
+type baseTemplate struct {
+	Name    string `json:"name"`
+	ID      string `json:"id"`
+	Content string `json:"-"`
+}
+
+var baseTemplates = []baseTemplate{fedora40WithSSH}
+
+var baseTemplateMap = map[string]baseTemplate{
+	"empty": {
+		Name:    "Empty",
+		ID:      "empty",
+		Content: "",
+	},
+	"fedora-40-openssh": fedora40WithSSH,
+}
+
+var fedora40WithSSH = baseTemplate{
+	Name: "Fedora 40 With OpenSSH Server",
+	ID:   "fedora-40-openssh",
+	Content: `FROM fedora:40
+
+RUN dnf install -y openssh-server \
+    && mkdir -p /etc/ssh \
+    && ssh-keygen -q -N "" -t rsa -b 4096 -f /etc/ssh/ssh_host_rsa_key \
+    && useradd testuser \
+    && echo "testuser:12345678" | chpasswd
+    && usermod -aG wheel testuser
+
+CMD ["/usr/sbin/sshd", "-D"]
+`,
+}