Reduziere SD-Karten-Schreiblast: leiser Agent + journald volatile

- Agent loggt im Normalfall nichts mehr (kein heartbeat_tick, kein
  mqtt_heartbeat_sent, kein status_report_sent)
- nur noch Fehler und Zustandsaenderungen werden geloggt
- Ansible: journald auf Storage=volatile + RuntimeMaxUse=20M (RAM-only,
  automatisches Verdraengen alter Eintraege bei vollem Puffer)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ansible/roles/signage_player/handlers/main.yml

@@ -4,6 +4,12 @@
     daemon_reload: true
   become: true
 
+- name: Restart journald
+  ansible.builtin.systemd:
+    name: systemd-journald
+    state: restarted
+  become: true
+
 - name: Restart morz-agent
   ansible.builtin.systemd:
     name: morz-agent

ansible/roles/signage_player/tasks/main.yml

@@ -50,6 +50,28 @@
     - Reload systemd
     - Restart morz-agent
 
+- name: Ensure journald drop-in directory exists
+  ansible.builtin.file:
+    path: /etc/systemd/journald.conf.d
+    state: directory
+    owner: root
+    group: root
+    mode: "0755"
+  become: true
+
+- name: Configure journald volatile storage (RAM only, schont SD-Karte)
+  ansible.builtin.copy:
+    dest: /etc/systemd/journald.conf.d/morz-volatile.conf
+    content: |
+      [Journal]
+      Storage=volatile
+      RuntimeMaxUse=20M
+    owner: root
+    group: root
+    mode: "0644"
+  become: true
+  notify: Restart journald
+
 - name: Enable and start morz-agent
   ansible.builtin.systemd:
     name: morz-agent

player/agent/internal/app/app.go

@@ -185,13 +185,9 @@ func (a *App) emitHeartbeat() {
 	connectivity := a.serverConnectivity
 	a.mu.Unlock()
 
-	a.logger.Printf("event=heartbeat_tick screen_id=%s", a.Config.ScreenID)
-
 	if a.mqttPub != nil {
 		if err := a.mqttPub.SendHeartbeat(string(status), string(connectivity), now); err != nil {
 			a.logger.Printf("event=mqtt_heartbeat_failed screen_id=%s error=%v", a.Config.ScreenID, err)
-		} else {
-			a.logger.Printf("event=mqtt_heartbeat_sent screen_id=%s", a.Config.ScreenID)
 		}
 	}
 }
@@ -233,5 +229,4 @@ func (a *App) reportStatus(ctx context.Context) {
 	a.consecutiveReportFailures = 0
 	a.serverConnectivity = ConnectivityOnline
 	a.mu.Unlock()
-	a.logger.Printf("event=status_report_sent screen_id=%s", a.Config.ScreenID)
 }

player/agent/internal/app/app_test.go

@@ -92,7 +92,6 @@ func TestAppRunUpdatesHealthAndLogsStructuredEvents(t *testing.T) {
 	for _, needle := range []string{
 		"event=agent_configured",
 		"screen_id=info01-dev",
-		"event=heartbeat_tick",
 		"event=agent_stopped",
 	} {
 		if !strings.Contains(logs, needle) {