feat: runtime config, Matomo analytics, chat accounts, DM history/search, and Prometheus retention

backend/chat/src/config/config.go

@@ -16,6 +16,7 @@ const (
 	DefaultRateLimitMax          = 10
 	DefaultRateLimitWindow       = 10 * time.Second
 	DefaultAdminSessionTTL       = 12 * time.Hour
+	DefaultUserSessionTTL        = 30 * 24 * time.Hour
 	DefaultChatPort              = "3000"
 )
 
@@ -68,6 +69,19 @@ func AdminSessionTTL() time.Duration {
 	return time.Duration(hours) * time.Hour
 }
 
+// UserSessionTTL returns the user session TTL from env or default (30 days).
+func UserSessionTTL() time.Duration {
+	raw := strings.TrimSpace(os.Getenv("USER_SESSION_TTL_HOURS"))
+	if raw == "" {
+		return DefaultUserSessionTTL
+	}
+	hours, err := strconv.Atoi(raw)
+	if err != nil || hours <= 0 {
+		return DefaultUserSessionTTL
+	}
+	return time.Duration(hours) * time.Hour
+}
+
 // RateLimitMax returns the chat rate limit max messages per window.
 func RateLimitMax() int {
 	raw := strings.TrimSpace(os.Getenv("CHAT_RATE_LIMIT_MAX"))