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.

scripts/package-boundaries.json

@@ -4817,6 +4817,17 @@
     ],
     "external": []
   },
+  "news-source": {
+    "exports": ["./layers/news/source"],
+    "modules": [
+      "src/layers/news/source.js",
+      "src/layers/news/records.js",
+      "src/sources/httpBody.js",
+      "src/sources/capability.js",
+      "src/i18n/marker.js"
+    ],
+    "external": []
+  },
   "perimeters-source": {
     "exports": ["./layers/perimeters/source"],
     "modules": [