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

group_vars/all/09_ports.yml

@@ -8,7 +8,6 @@ ports:
     websocket:
       web-app-mastodon:   4001
       web-app-espocrm:    4002
-      web-app-nextcloud:  4003
     oauth2_proxy:
       web-app-phpmyadmin: 4181
       web-app-lam: 4182
@@ -24,11 +23,10 @@ ports:
     http:
       # Ports which are exposed to the World Wide Web
       web-app-nextcloud: 8001
-      # web-app-nextcloud_talk: 8005
-      # web-app-nextcloud_whiteboard: 8015
       web-app-gitea: 8002
       web-app-wordpress: 8003
       web-app-mediawiki: 8004
+      # Free : 8005
       web-app-yourls: 8006
       web-app-mailu: 8007
       web-app-elk: 8008
@@ -38,6 +36,7 @@ ports:
       web-app-funkwhale: 8012
       web-app-roulette-wheel: 8013
       web-app-joomla: 8014
+      # Free: 8015
       web-app-pgadmin: 8016
       web-app-baserow: 8017
       web-app-matomo: 8018
@@ -81,9 +80,10 @@ ports:
       svc-db-openldap: 636
     stun:
       web-app-bigbluebutton: 3478    # Not sure if it's right placed here or if it should be moved to localhost section
-      web-app-nextcloud: 3479
+      # Occupied by BBB:     3479
+      web-app-nextcloud:     3480
     turn:
       web-app-bigbluebutton: 5349    # Not sure if it's right placed here or if it should be moved to localhost section
-      web-app-nextcloud: 5350        # Not used yet
+      web-app-nextcloud:     5350        # Not used yet
     federation:
       web-app-matrix_synapse: 8448