config(csaxs): adjust sl1xs epics offset

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017NrH3poJsYBCTVq2Y9fuHZ

csaxs_bec/device_configs/bl_frontend.yaml

@@ -115,7 +115,7 @@ sl1xs:
   readOnly: false
   softwareTrigger: false
   userParameter:
-    epics_offset: 0.010525
+    epics_offset: -0.0021
   deviceTags:
     - bl_frontend