Replace RCON with API-only emulator transport

- Switch default EMULATOR_MODE from 'rcon' to 'api'
- Remove RCON_HOST/PORT/timeout/maxRetries env vars
- Add EMULATOR_API_URL to .env and .env.example
- Update createEmulatorTransport() to use HTTP API only
- Remove rconHost/port from offline alert context
- All 827 tests pass, TypeScript compiles cleanly

.env.example

@@ -46,11 +46,8 @@ DB_BACKUP_KEEP=7
 # Minutes between repeat health-fail alerts from jobs-worker (default 15).
 HEALTH_ALERT_COOLDOWN_MIN=15
 
-# --- RCON (Low Latency Loop) ---
-RCON_HOST=127.0.0.1
-RCON_PORT=3003
-EMU_PORT=3004
-RCON_TIMEOUT_MS=2000
+# --- EMULATOR API ---
+EMULATOR_API_URL=http://127.0.0.1:3001
 
 # --- EMAIL & NOTIFICATIONS ---
 SMTP_HOST=