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]>

CHANGELOG.md

@@ -155,11 +155,18 @@
   largest cities) and `CCTV_VEGVESEN_VIDEO=0` keeps stills only. Attributed
   under NLOD 2.0.
 
-- GNSS Interference layer (Events group): ADS-B aircraft that report degraded
-  navigation accuracy (below the 14 CFR 91.227 ADS-B Out minima, NIC < 7 or
-  NACp < 8, or readsb's GPS-loss flag) are binned into 0.5° cells over a
-  rolling 30-minute window and scored with gpsjam.org's published formula and
-  bands. Keyless, worldwide wherever adsb.lol has receivers; reads
+- GNSS Integrity layer (Events group, share id `gnss-interference`): cells of
+  low navigation accuracy reported by ADS-B aircraft. The method is a GEV
+  threshold plus gpsjam.org aggregation, not "the gpsjam method": an aircraft
+  counts as low when it reports NIC < 7 or NACp < 8 (borrowed from the US
+  14 CFR 91.227 ADS-B Out minima, not a published interference classifier) or
+  readsb's GPS-loss flag; aircraft are binned into 0.5° cells over a
+  GEV-defined rolling 30-minute window around visited views and scored with
+  gpsjam.org's published formula and 2% / 10% bands. Medium and high cells
+  are navigation-integrity anomalies; suspected GNSS interference is a
+  secondary, unvalidated interpretation. The layer and the proxy expose
+  machine-readable provenance (`provenance`, `classifier: gev-nic-nacp-v1`).
+  Keyless, worldwide wherever adsb.lol has receivers; reads
   a capped 250 nm snapshot around the camera through `/api/gnss-integrity`,
   which returns integrity fields only and serves the last snapshot when the
   upstream fails.