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>

web/pages/jobs/[jobId].tsx

@@ -2,7 +2,7 @@ import { useRouter } from 'next/router';
 import { useCallback, useEffect, useState } from 'react';
 import Layout from '../../components/Layout';
 import JobMap from '../../components/map/JobMap';
-import type { MapPoint } from '../../components/map/types';
+import { pointSummary, type MapPoint } from '../../components/map/types';
 import { api } from '../../lib/api';
 import { useRequireAuth } from '../../lib/auth-context';
 import { useJobStream } from '../../lib/use-job-stream';
@@ -98,13 +98,16 @@ export default function JobDetailPage() {
           </p>
           {job.description && <p>{job.description}</p>}
 
-          <div style={{ margin: '1rem 0', display: 'flex', gap: '1rem', color: '#555' }}>
+          <div style={{ margin: '1rem 0', display: 'flex', gap: '1rem', color: '#555', flexWrap: 'wrap' }}>
             <span>
               <strong>{points.length}</strong> points
             </span>
             <span style={{ color: live > 0 ? '#388e3c' : '#999' }}>
               ● live{live > 0 ? ` (+${live} this session)` : ''}
             </span>
+            {points.length > 0 && (
+              <span style={{ color: '#777' }}>latest: {pointSummary(points[points.length - 1])}</span>
+            )}
           </div>
 
           <JobMap points={points} heightPx={520} />