Nextcloud: integrate Talk & Whiteboard; adjust ports & healthchecks

- Enable Spreed (Talk); signaling via /standalone-signaling/
- STUN/TURN: move STUN to 3480 (3479 occupied by BBB), keep TURN 5350 reserved
- docker-compose: expose internal WS ports; explicit TURN port mapping
- Healthchecks: add nc-based TCP checks (roles/docker-container/templates/healthcheck/nc.yml.j2)
- Nginx: location proxy to talk:8081
- Schema: add talk_* secrets (turn/signaling/internal)
- Plugins: configure spreed/whiteboard via vars/*; remove old task files
- Ports matrix (group_vars/all/09_ports.yml) updated/commented

Conversation: https://chatgpt.com/share/68b61a6a-e1dc-800f-b793-4aa600bc0166

roles/web-app-nextcloud/vars/plugins/spreed.yml

@@ -0,0 +1,23 @@
+plugin_configuration:
+  - appid: "spreed"
+    configkey: "signaling_servers"
+    configvalue:
+      - server: "{{ NEXTCLOUD_TALK_URL }}"
+        verify: true
+        # optional:
+        alias: "primary"
+
+  # STUN
+  - appid: "spreed"
+    configkey: "stun_servers"
+    configvalue:
+      - "stun:{{ NEXTCLOUD_TALK_DOMAIN }}:{{ NEXTCLOUD_TALK_STUN_PORT }}"
+
+  # TURN with REST-Secret (used by Talk/Coturn)
+  - appid: "spreed"
+    configkey: "turn_servers"
+    configvalue:
+      - server: "turn:{{ NEXTCLOUD_TALK_DOMAIN }}:{{ NEXTCLOUD_TALK_STUN_PORT }}?transport=udp"
+        secret: "{{ applications | get_app_conf(application_id, 'credentials.talk_turn_secret') }}"
+        ttl: 86400
+        protocols: "udp,tcp"

roles/web-app-nextcloud/vars/plugins/whiteboard.yml

@@ -0,0 +1,8 @@
+plugin_configuration:
+  - appid: "whiteboard"
+    configkey: "collabBackendUrl"
+    configvalue: "{{ NEXTCLOUD_WHITEBOARD_URL }}"
+
+  - appid: "whiteboard"
+    configkey: "jwt_secret_key"
+    configvalue: "{{ NEXTCLOUD_WHITEBOARD_JWT }}"