Replace # with - in Zabbix host names (Zabbix 7.x compatibility)

Zabbix 7.x rejects '#' in host names. Changed hostname format from
'yodeck#<id>' to 'yodeck-<id>' (e.g. yodeck-54239).
Updated SNMP col 1 value and docs for consistency.

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

app/zabbix.py

@@ -2,7 +2,7 @@
 Zabbix API client for automatic host management.
 
 Each Yodeck player becomes a Zabbix host with:
-  - hostname  : yodeck#<yodeck_id>
+  - hostname  : yodeck-<yodeck_id>
   - visible name: "QRS-" + the Yodeck player's display name (e.g. QRS-AMS-COF1)
   - SNMP v2c interface pointing to this app (APP_HOST:161)
   - Four SNMP items: online, last_seen, updating, registered
@@ -171,7 +171,7 @@ def sync_to_zabbix(players, add_log_fn):
         created = updated = 0
         for player in players:
             yid      = player['id']
-            hostname = f"yodeck#{yid}"
+            hostname = f"yodeck-{yid}"
             visible  = f"QRS-{player['name']}"
 
             if hostname not in existing: