fix(console): switch ser2net accepter to telnet(rfc2217) for proper NVT

The original ser2net config used raw TCP accepters, but conman's
dev="host:port" speaks telnet protocol. This protocol mismatch caused
conman's telnet NVT state machine to strip bare CR characters from
device output — particularly from Dell switches that send \n\r (LF+CR)
line endings — producing stair-stepped and garbled terminal display.

Fix: change ser2net accepter from `tcp,IP,PORT` to
`telnet(rfc2217),tcp,IP,PORT`. With both sides speaking telnet, binary
mode is negotiated and CR/LF translation is handled correctly by the
telnet NVT layer. RFC2217 also enables baud rate negotiation for
future use.

Validated at the byte level: PTY capture confirms all prompts render
cleanly at column 0 with proper CRLF handling across 5+ Enter presses.
All 7 consoles connected, 7 log files actively capturing.

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

console/generate-config.sh

@@ -159,7 +159,9 @@ fi
 
   for entry in "${ENTRIES[@]}"; do
     IFS='|' read -r tcp_port name id_path baud comment <<< "$entry"
-    # ser2net connection block — telnet(rfc2217) accepter for proper NVT handling
+    # ser2net connection block — telnet(rfc2217) accepter so conman and
+    # telnet clients negotiate proper telnet binary mode. This prevents
+    # CR stripping that occurs with raw TCP + conman's telnet NVT.
     echo "connection: &con${tcp_port}"
     echo "    accepter: telnet(rfc2217),tcp,${TS_IP},${tcp_port}"
     echo "    enable: on"