traefik: de-secret CrowdSec LAPI key -> crowdsecLapiKeyFile (rotated)

Old bouncer key was committed in cleartext (hist 7fac4fc) and is now rotated
(new traefik-bouncer-v2 + old bouncer deleted, verified 200 on both nodes).
Config now references /plugins-storage/crowdsec_lapi_key (mode-600, gitignored,
lives only on the nodes). Old key in history is inert post-rotation.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

traefik/dynamic_conf_node01.yml

@@ -79,7 +79,7 @@ http:
       plugin:
         crowdsec-bouncer:
           enabled: true
-          crowdsecLapiKey: VMCnws/j+9pmsT4YT+t3HzrvX8OhBCwoquwo4NqWJPs
+          crowdsecLapiKeyFile: /plugins-storage/crowdsec_lapi_key
           crowdsecLapiHost: crowdsec:8080
           crowdsecMode: live