fix: cert check on connect, force IPv4, clean up bridge.sh default IP

- Raise FileNotFoundError with clear message when TLS certs are missing
  rather than a cryptic SSL error
- Use getaddrinfo(AF_INET) before create_connection to force IPv4 and
  avoid dual-stack resolution failures on some networks
- Comment out hardcoded PRINTER_IP in bridge.sh

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

VERSION

@@ -1 +1 @@
-0.9.18
+0.9.21

bridge.sh

@@ -2,7 +2,7 @@
 # Bridge-Manager: start | stop | restart | status | log
 SCRIPT="$(dirname "$0")/kobrax_moonraker_bridge.py"
 LOGFILE="/tmp/bridge.log"
-PRINTER_IP="192.168.178.94"
+# PRINTER_IP="192.168.178.94"
 
 case "${1:-restart}" in
   start)

kobrax_client.py

@@ -154,13 +154,21 @@ class KobraXClient:
     # -- Connection ----------------------------------------------------------
 
     def _do_connect(self):
+        if not os.path.exists(CERT_FILE) or not os.path.exists(KEY_FILE):
+            raise FileNotFoundError(
+                f"TLS-Zertifikate fehlen: anycubic_slicer.crt + anycubic_slicer.key "
+                f"müssen neben der kx-bridge Binary liegen ({_SCRIPT_DIR}/). "
+                f"Lade anycubic-certs.zip vom Gitea-Release herunter und entpacke "
+                f"die Dateien dorthin."
+            )
         ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
         ctx.check_hostname = False
         ctx.verify_mode    = ssl.CERT_NONE
         ctx.set_ciphers("DEFAULT:@SECLEVEL=0")
         ctx.load_cert_chain(CERT_FILE, KEY_FILE)
 
-        raw        = socket.create_connection((self.host, self.port), timeout=5)
+        _ai        = socket.getaddrinfo(self.host, self.port, socket.AF_INET, socket.SOCK_STREAM)
+        raw        = socket.create_connection(_ai[0][4], timeout=5)
         self._sock = ctx.wrap_socket(raw)
         log.info("TLS connected  cipher=%s", self._sock.cipher()[0])
 
@@ -589,7 +597,8 @@ class KobraXClient:
         # langsamerem WLAN am Drucker dauert das Schieben sonst >30 s und
         # würde den Connect-Timeout fälschlich auslösen. Read-Timeout danach
         # generös (Drucker verarbeitet die Datei bevor er antwortet).
-        sock = socket.create_connection((self.host, 18910), timeout=10)
+        _ai  = socket.getaddrinfo(self.host, 18910, socket.AF_INET, socket.SOCK_STREAM)
+        sock = socket.create_connection(_ai[0][4], timeout=10)
         sock.settimeout(None)  # blocking während Send
         sock.sendall(headers + body)
         sock.settimeout(180)