fix(gnss): separate GEV integrity classifier from GPSJAM aggregation; machine-readable provenance

Review on #855: the per-aircraft rule (NIC < 7 || NACp < 8, borrowed from
the US 14 CFR 91.227 ADS-B Out minima) is GEV-defined, not gpsjam's, and
gpsjam's map shows low navigation accuracy, not necessarily jamming.

- Primary cell state is now `navigation-integrity-anomaly` (medium/high) or
  `nominal`; `suspected-gnss-interference` is a secondary `interpretation`
  marked validated: false.
- GNSS_PROVENANCE / gnssProvenance({ windowMs }) records the classifier
  (gev-nic-nacp-v1, GEV, unvalidated), the gpsjam aggregation (formula,
  bands [0.02, 0.1], FAQ source) and the GEV 30-minute visited-view window,
  built from the constants the code applies. Exposed as layer.provenance
  and getStats().provenance; the proxy tags responses with `classifier`.
- Visible name "GNSS Integrity", legend "... low accuracy", blurb leads with
  low navigation accuracy and states the threshold is a GEV choice.
- Layer id `gnss-interference` and share token `0` unchanged.
- Voice aliases add "gnss integrity", "navigation integrity",
  "low navigation accuracy"; the interference aliases stay.
- Docs describe the method as GEV threshold + gpsjam aggregation.
- Tests: provenance object, renamed state/label, proxy classifier tag;
  qa-gnss asserts provenance and wording in the real app.

Hex project - Crew Leo Agile dev team.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

src/layers/gnss/source.test.mjs

@@ -8,7 +8,11 @@ test('the source asks the same-origin proxy for the view anchor', async () => {
     fetchImpl: async (url, options) => {
       calls.push(url);
       assert.ok(options.signal instanceof AbortSignal);
-      return Response.json({ fetchedAt: 5, rows: [{ hex: 'abc123' }] });
+      return Response.json({
+        fetchedAt: 5,
+        classifier: 'gev-nic-nacp-v1',
+        rows: [{ hex: 'abc123' }],
+      });
     },
   });
   const snapshot = await source.getSnapshot(
@@ -20,6 +24,7 @@ test('the source asks the same-origin proxy for the view anchor', async () => {
     rows: [{ hex: 'abc123' }],
     fetchedAt: 5,
     stale: false,
+    classifier: 'gev-nic-nacp-v1',
   });
 });
 
@@ -30,6 +35,7 @@ test('the source reports stale proxy data and rejects bad input or responses', a
   }).getSnapshot({ latitude: 1, longitude: 2 });
   assert.equal(stale.stale, true);
   assert.equal(stale.fetchedAt, null);
+  assert.equal(stale.classifier, null);
 
   await assert.rejects(
     createAdsbGnssSource({ fetchImpl: reply({}) }).getSnapshot({}),