feat(layers): add shipwrecks layer (EMODnet + Wikidata)

A new Events layer maps shipwrecks with a card per wreck:
- EMODnet Human Activities heritage shipwrecks (about 6,500 in European
  waters, CC BY 4.0), skipping rows taken from wrecksite.eu.
- Wikidata shipwrecks with a Wikipedia article plus sinking events
  (CC0); an event folds into its ship for the date and death toll.
- A same-origin /api/shipwrecks proxy refreshes once a day and serves
  the last snapshot as stale for up to a week.

Markers are a boat icon coloured by era and sized by deaths; four era
chips filter the layer. The card follows the air-accidents layout
(deaths first). Text that names people is dropped; victims appear as
a count only.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

server/providers/local.js

@@ -28,6 +28,7 @@ import { weatherProxy } from './weather.js';
 import { firePerimetersProxy } from './firePerimeters.js';
 import { gnssIntegrityProxy } from './gnssIntegrity.js';
 import { ghostMapsProxy } from './ghostMaps.js';
+import { shipwrecksProxy } from './shipwrecks.js';
 import { droneAirspaceProxy } from './droneAirspace.js';
 import { cycloneProxy } from './cyclones.js';
 import { windProxy } from './wind.js';
@@ -80,6 +81,7 @@ function localProviderPlugins({
     firePerimetersProxy(),
     gnssIntegrityProxy(),
     ghostMapsProxy(),
+    shipwrecksProxy(),
     droneAirspaceProxy(),
     keySetupEndpoint(),
   ];