feat: add deploy webhook endpoint (POST /api/v1/_deploy)

internal/config/config.go

@@ -23,6 +23,7 @@ type Config struct {
 	LLMEndpoint     string
 	GoogleClientID  string
 	JWTSecret       string
+	DeploySecret    string
 }
 
 func LoadFromEnv() Config {
@@ -38,6 +39,7 @@ func LoadFromEnv() Config {
 		LLMEndpoint:     envOrDefault("TUTOR_LLM_ENDPOINT", ""),
 		GoogleClientID:  envOrDefault("GOOGLE_CLIENT_ID", ""),
 		JWTSecret:       envOrDefault("JWT_SECRET", ""),
+		DeploySecret:    envOrDefault("TUTOR_DEPLOY_SECRET", ""),
 	}
 }
 
@@ -45,6 +47,10 @@ func (c Config) HasLLM() bool {
 	return c.LLMEndpoint != ""
 }
 
+func (c Config) HasDeploy() bool {
+	return c.DeploySecret != ""
+}
+
 func envOrDefault(key string, fallback string) string {
 	value := os.Getenv(key)
 	if value == "" {