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]>

server/providers/gnssIntegrity.js

@@ -1,4 +1,7 @@
-import { normalizeGnssAircraft } from '../../src/layers/gnss/records.js';
+import {
+  GNSS_CLASSIFIER,
+  normalizeGnssAircraft,
+} from '../../src/layers/gnss/records.js';
 import { adsbLolFallbackAnchor } from './aircraft/opensky.js';
 import { coalesceProxyRequest, readResponseJsonCapped } from './common/http.js';
 import { makeRateLimiter, clientKey } from './common/rate-limit.js';
@@ -91,6 +94,8 @@ export function gnssIntegrityProxy({
       fetchedAt: now(),
       anchor: { lat, lon },
       radiusNm: RADIUS_NM,
+      // `degraded` on each row is this classifier's verdict, not gpsjam's.
+      classifier: GNSS_CLASSIFIER.id,
       rows,
     };
   }