feat(canon): add a sim-only session config for offline work

Working on the camera away from the beamline meant loading a full cSAXS
session and then ignoring everything in it. This config is a complete
session containing nothing but the simulated camera, so no beamline motor
or detector is defined at all and none can be addressed by accident.

The real ptz_cam is deliberately absent: it lives at an X12SA address that
is not routable off the beamline network, so including it would only
produce connection errors at every startup. canon_crn300.yaml remains the
config for a beamline host.

stream_start is "connect" rather than "stage" -- with readoutPriority
on_request the device is excluded from staging, so "stage" would never
fire.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KLnmUurqcNd1FiDY5M2uZr

csaxs_bec/device_configs/canon_laptop_sim.yaml

@@ -0,0 +1,34 @@
+# Canon CR-N300 -- laptop / offline development session.
+#
+# A complete BEC session containing nothing but the simulated camera, for working on
+# the device off the beamline. Load it with:
+#
+#     bec.config.update_session_with_file(
+#         "<checkout>/csaxs_bec/device_configs/canon_laptop_sim.yaml")
+#
+# This REPLACES the active session, which is the point: no beamline motors or
+# detectors are defined, so nothing here can address hardware even by accident.
+#
+# The real camera is deliberately absent. It lives at an X12SA address that is not
+# routable from a laptop, and including it would only produce connection errors on
+# every startup. Use canon_crn300.yaml on a beamline host for the real device.
+
+ptz_cam_sim:
+  description: Canon CR-N300 PTZ camera (simulation, no hardware required)
+  deviceClass: csaxs_bec.devices.canon.canon_ptz.CanonPTZCamera
+  deviceConfig:
+    simulation: true
+    gradual_motion: true       # finite-speed travel, so move statuses are exercised
+    buffer_maxlen: 32
+    acquisition_mode: "jpeg_poll"
+    poll_rate: 5.0             # faster than the real 2 Hz default; keeps the sim lively
+    stream_start: "connect"    # NOT "stage" -- see readoutPriority below
+  deviceTags:
+    - camera
+    - ptz
+    - simulation
+  enabled: true
+  onFailure: buffer
+  readOnly: false
+  readoutPriority: on_request
+  softwareTrigger: false