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>

backend/src/ingest/dto/mqtt-messages.dto.ts

@@ -139,6 +139,15 @@ export class MqttPointsMessageDto {
   points: MqttPointDto[];
 }
 
+// Single-reading log entry for a locator that publishes directly (or is
+// relayed) to devices/<serial>/log — the serial comes from the topic itself,
+// so identity is job-anchored rather than publisher-credential-anchored.
+export class MqttLogMessageDto extends MqttPointDto {
+  @IsString()
+  @IsNotEmpty()
+  jobId: string;
+}
+
 export class MqttJobMessageDto {
   @IsString()
   @IsNotEmpty()