Tie points to locator serial numbers and store receiver telemetry

Adds devices/<serial>/log as a job-anchored MQTT ingest path: a locator
identifies itself by serial in the topic (auto-registered on first
sight, org resolved from the job in the payload) rather than by a
pre-provisioned broker credential. Device.serialNumber is now globally
unique so the bare topic segment is enough to resolve identity.
Locator lookup/auto-register logic is shared (LocatorRegistryService)
between this and the existing devices/<mqttUsername>/points path.

New /sim page (own header, outside the main app nav) simulates a
transmitter: pick an open job or create one, set a serial number and
telemetry defaults, and send points one at a time or on an interval
along a simulated walking path. It calls a new authenticated backend
endpoint (POST /orgs/:orgId/sim/publish) that publishes onto the real
broker rather than writing the DB directly, so the simulator exercises
the actual ingest pipeline end-to-end.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

mosquitto/config/devices.acl

@@ -11,9 +11,11 @@ user admin
 topic readwrite #
 topic readwrite $SYS/#
 
-# Backend service: reads all device traffic, writes job acks back to devices
+# Backend service: reads all device traffic, writes job acks back to devices,
+# and publishes on behalf of the /sim simulator tool (devices/<serial>/log)
 user backend
 topic read devices/#
 topic write devices/+/jobs/ack
+topic write devices/+/log
 
 # testuser is a demo *device*: only the per-device pattern rule above applies