feat: Wildlife Sightings layer from iNaturalist and Acartia

Recent community wildlife observations, as a new Wildlife group in the
layer panel.

- Server: keyless iNaturalist proxy (v2 observations with only the
  projected fields; undocumented v1 UTFGrid density tiles, decoded on the
  server) sharing one paced queue (burst 4, ~1/s, 60/min, 8,000/day budget,
  up to four in flight), in-memory caches and upstream-only cooldowns;
  Acartia Salish Sea marine-mammal feed rounded to 0.01 degrees with
  comments dropped.
- Layer: grid counts drawn as a soft view-ranked density glow; real sampled
  sightings as taxon badges at their true positions with ambient photo
  thumbnails and labels; obscured records stay privacy cells; a clicked
  sighting stays pinned through camera moves and refreshes.
- Anchored photo card per selection with the single iNaturalist link;
  attribution in the layer row and the Data attribution popover.
- Filters (CONFIRMED, taxa presets) round-trip in share links with token 9.

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

server/providers/inaturalist/proxy.fixture.mjs

@@ -0,0 +1,70 @@
+import assert from 'node:assert/strict';
+import { EventEmitter } from 'node:events';
+import { inaturalistProxy } from './observations.js';
+
+export const NOW = Date.parse('2026-11-04T18:05:00Z');
+
+/** Mount the proxy over synthetic HTTP objects, without opening a socket. */
+export function installInatProxy(
+  defaultUrl,
+  options = {},
+  hook = 'configureServer',
+) {
+  let handler;
+  const plugin = inaturalistProxy({
+    now: () => NOW,
+    cacheDir: null,
+    queueOptions: { intervalMs: 0, windowMs: 0 },
+    warn() {},
+    ...options,
+  });
+  assert.equal(plugin.name, 'inaturalist');
+  assert.equal(typeof plugin.configureServer, 'function');
+  assert.equal(typeof plugin.configurePreviewServer, 'function');
+  plugin[hook]({
+    middlewares: {
+      use(mount, callback) {
+        assert.equal(mount, '/api/inaturalist');
+        handler = callback;
+      },
+    },
+  });
+  return async (
+    url = defaultUrl,
+    { method = 'GET', peer = 'local', headers = {}, signal } = {},
+  ) => {
+    const res = Object.assign(new EventEmitter(), {
+      headers: {},
+      writeHead(status, headers) {
+        this.status = status;
+        Object.assign(this.headers, headers);
+      },
+      setHeader(key, value) {
+        this.headers[key] = value;
+      },
+      end(value) {
+        this.status ??= this.statusCode;
+        this.body = JSON.parse(value);
+      },
+    });
+    const abort = () => {
+      res.destroyed = true;
+      res.emit('close');
+    };
+    signal?.addEventListener('abort', abort, { once: true });
+    try {
+      await handler(
+        Object.assign(new EventEmitter(), {
+          url,
+          method,
+          headers,
+          socket: { remoteAddress: peer },
+        }),
+        res,
+      );
+    } finally {
+      signal?.removeEventListener('abort', abort);
+    }
+    return res;
+  };
+}