Add Zabbix template with offline and last-seen triggers

- zabbix_template.yaml: importable template "Yodmon Yodeck Player"
  - 5 SNMP items using {$YODECK_ID} host macro for per-host OIDs
  - Trigger: offline warning after 30 minutes (yodeck.online < 1)
  - Trigger: last seen > 4 hours (now() - yodeck.last_seen_ts > 14400)
- snmp/pass_persist.py: add col 7 — last_seen as Unix timestamp
- app/zabbix.py: link hosts to template, upsert {$YODECK_ID} macro;
  existing hosts get template linked on next sync automatically
- app/config.py: add ZABBIX_TEMPLATE setting

Import zabbix_template.yaml once via Zabbix UI, then redeploy.

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

snmp/pass_persist.py

@@ -7,10 +7,11 @@ Reads player data from the SQLite database and serves it over SNMP v2c.
 OID layout  (base = ENTERPRISE_OID.1.1):
   base.1.<yodeck_id>  STRING   "yodeck-<id>"
   base.2.<yodeck_id>  STRING   player display name
-  base.3.<yodeck_id>  INTEGER  online     (1 = online, 0 = offline)
-  base.4.<yodeck_id>  STRING   last_seen  (ISO-8601 timestamp)
-  base.5.<yodeck_id>  INTEGER  updating   (1 = yes, 0 = no)
-  base.6.<yodeck_id>  INTEGER  registered (1 = yes, 0 = no)
+  base.3.<yodeck_id>  INTEGER  online          (1 = online, 0 = offline)
+  base.4.<yodeck_id>  STRING   last_seen       (ISO-8601 timestamp)
+  base.5.<yodeck_id>  INTEGER  updating        (1 = yes, 0 = no)
+  base.6.<yodeck_id>  INTEGER  registered      (1 = yes, 0 = no)
+  base.7.<yodeck_id>  INTEGER  last_seen_unix  (Unix timestamp, 0 if unknown)
 
 pass_persist protocol (net-snmp):
   stdin:  PING | get\n<oid> | getnext\n<oid>
@@ -25,6 +26,17 @@ DB_PATH        = os.environ.get('DB_PATH', '/data/yodmon.db')
 ENTERPRISE_OID = os.environ.get('ENTERPRISE_OID', '.1.3.6.1.4.1.99999')
 BASE_OID       = f"{ENTERPRISE_OID}.1.1"
 
+def _iso_to_unix(iso_str):
+    """Convert ISO-8601 timestamp string to Unix epoch integer, 0 if missing."""
+    if not iso_str:
+        return 0
+    try:
+        dt = datetime.fromisoformat(iso_str.replace('Z', '+00:00'))
+        return int(dt.timestamp())
+    except Exception:
+        return 0
+
+
 # (column_index, snmp_type, value_extractor)
 COLUMNS = [
     (1, 'STRING',  lambda p: f"yodeck-{p['id']}"),
@@ -33,6 +45,7 @@ COLUMNS = [
     (4, 'STRING',  lambda p: p.get('last_seen') or ''),
     (5, 'INTEGER', lambda p: str(p.get('updating', 0))),
     (6, 'INTEGER', lambda p: str(p.get('registered', 0))),
+    (7, 'INTEGER', lambda p: str(_iso_to_unix(p.get('last_seen')))),
 ]
 
 # Rate-limit SNMP transfer log entries (at most one per minute)