feat: Telegram OSINT map layer, Osiris intel ports, and maritime settings

Add Telegram OSINT with hourly incremental t.me scraping, metro geocoding
separate from news centroids, threat-intercept popup UI with inline media,
and HTML markers above alert boxes so pins stay clickable. Expose GFW_API_TOKEN
in onboarding and Settings Maritime; harden GFW/CCTV/geo fetchers. Port Osiris-
derived recon, SCM, entity graph, malware/cyber feeds, sanctions, and submarine
cable layers with tests and documentation.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_datacenters_fetch.py

@@ -0,0 +1,10 @@
+"""Datacenters load from static JSON regardless of layer toggle."""
+from services.fetchers import _store
+from services.fetchers.infrastructure import fetch_datacenters
+
+
+def test_fetch_datacenters_populates_store_when_layer_disabled(monkeypatch):
+    monkeypatch.setitem(_store.active_layers, "datacenters", False)
+    _store.latest_data["datacenters"] = []
+    fetch_datacenters()
+    assert len(_store.latest_data.get("datacenters") or []) > 0