Add the news report model, markers and source

The pure half of a news layer: validated records for a news server's
`/api/news/hotspots|feed|outline` contract, a presentation model and canvas
markers and picture cards, and a fetch client.

- Colour carries severity only (0 no physical event, 1 minor, 2 significant,
  3 major), never a side; the category is the icon, the rim is attestation
  (confirmed, a claim, one side's own press), size grows with sources and
  markers fade with age.
- Cards say "Reported by {side} sources" and mark official channels; a
  machine-read English headline is labelled as such.
- `createNewsSource` reads same-origin routes with a 15 s timeout, a 4 MiB cap
  and record-by-record validation; `NEWS_API_PATHS` and `newsQueryAllowed`
  let a host proxy exactly what the client sends. A 503 marked unavailable
  means "not configured": no retries.
- Exported as `./layers/news/source`, with its own package boundary.

package.json

@@ -257,6 +257,7 @@
     "./layers/gnss/source": "./src/layers/gnss/source.js",
     "./layers/ghostmaps/source": "./src/layers/ghostMaps/source.js",
     "./layers/drone-airspace/source": "./src/layers/droneAirspace/source.js",
+    "./layers/news/source": "./src/layers/news/source.js",
     "./layers/firms/source": "./src/layers/firms/source.js",
     "./layers/installations/source": "./src/layers/installations/source.js",
     "./layers/launches/source": "./src/layers/launches/source.js",