Tie points to locator serial numbers and store receiver telemetry

Field setups often relay through a phone/gateway that owns the MQTT
connection, so the publishing credential and the instrument are now
separate concepts:

- Points messages carry a "serial" identifying the locator receiver;
  unknown serials are auto-registered as devices in the publisher's
  org (name "Locator <serial>"). Device.mqttUsername is now optional
  and serialNumber is unique per org.
- LocatePoint gains standard receiver telemetry: frequencyHz,
  currentMa, signalDb, gainDb, locateMode (PEAK/NULL/BROAD_PEAK/SONDE),
  phaseDeg, compassDeg, distortionPct, plus GPS quality columns
  vAccuracy, satellites, hdop. All optional; raw payload still kept.
- Migration hand-edited to preserve the generated geom column and its
  GIST index (Prisma diff wanted to drop both).
- REST create/point DTOs, map tooltips, job-detail latest-point
  readout, devices settings form, seed, and the sample publisher all
  carry the new fields.
- Added .dockerignore for backend/web: COPY . . was clobbering the
  image's freshly generated Prisma client with the host's stale
  node_modules, breaking image builds after schema changes.

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

backend/prisma/seed.ts

@@ -1,4 +1,4 @@
-import { PrismaClient, GpsFixType, JobStatus, UtilityType } from '@prisma/client';
+import { PrismaClient, GpsFixType, JobStatus, LocateMode, UtilityType } from '@prisma/client';
 import * as bcrypt from 'bcryptjs';
 
 const prisma = new PrismaClient();
@@ -68,7 +68,17 @@ async function main() {
       altitude: 187.4 + i * 0.02,
       fixType: GpsFixType.FIXED_RTK,
       hAccuracy: 0.014,
+      vAccuracy: 0.021,
+      satellites: 22,
+      hdop: 0.7,
       depth: 1.2,
+      frequencyHz: 33000,
+      currentMa: 48.5 - i * 0.4,
+      signalDb: 62.1 - i * 0.3,
+      gainDb: 40,
+      locateMode: LocateMode.PEAK,
+      compassDeg: 17.5,
+      distortionPct: 4.2,
       utilityType: UtilityType.GAS,
       sequence: i + 1,
       recordedAt: new Date(Date.now() - (12 - i) * 5000),