v0.7.0: performance hardening — parallel fetches, deferred icons, AIS stability

Optimizations:
- Parallelized yfinance stock/oil fetches via ThreadPoolExecutor (~2s vs ~8s)
- AIS backoff reset after 200 successes; removed hot-loop pruning (lock contention)
- Single-pass ETag serialization (was double-serializing JSON)
- Deferred ~50 non-critical map icons via setTimeout(0)
- News feed animation capped at 15 items (was 100+ simultaneous)
- heapq.nlargest() for FIRMS fires (60K→5K) and internet outages
- Removed satellite duplication from fast endpoint
- Geopolitics interval 5min → 30min
- Ship counts single-pass memoized; color maps module-level constants
- Improved GDELT URL-to-headline extraction (skip gibberish slugs)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Former-commit-id: 4a14a2f078

backend/config/news_feeds.json

@@ -1,12 +1,44 @@
 {
   "feeds": [
-    { "name": "NPR", "url": "https://feeds.npr.org/1004/rss.xml", "weight": 4 },
-    { "name": "BBC", "url": "http://feeds.bbci.co.uk/news/world/rss.xml", "weight": 3 },
-    { "name": "AlJazeera", "url": "https://www.aljazeera.com/xml/rss/all.xml", "weight": 2 },
-    { "name": "NYT", "url": "https://rss.nytimes.com/services/xml/rss/nyt/World.xml", "weight": 1 },
-    { "name": "GDACS", "url": "https://www.gdacs.org/xml/rss.xml", "weight": 5 },
-    { "name": "NHK", "url": "https://www3.nhk.or.jp/nhkworld/rss/world.xml", "weight": 3 },
-    { "name": "CNA", "url": "https://www.channelnewsasia.com/rssfeed/8395986", "weight": 3 },
-    { "name": "Mercopress", "url": "https://en.mercopress.com/rss/", "weight": 3 }
+    {
+      "name": "NPR",
+      "url": "https://feeds.npr.org/1004/rss.xml",
+      "weight": 4
+    },
+    {
+      "name": "BBC",
+      "url": "http://feeds.bbci.co.uk/news/world/rss.xml",
+      "weight": 3
+    },
+    {
+      "name": "AlJazeera",
+      "url": "https://www.aljazeera.com/xml/rss/all.xml",
+      "weight": 2
+    },
+    {
+      "name": "NYT",
+      "url": "https://rss.nytimes.com/services/xml/rss/nyt/World.xml",
+      "weight": 1
+    },
+    {
+      "name": "GDACS",
+      "url": "https://www.gdacs.org/xml/rss.xml",
+      "weight": 5
+    },
+    {
+      "name": "NHK",
+      "url": "https://www3.nhk.or.jp/nhkworld/rss/world.xml",
+      "weight": 3
+    },
+    {
+      "name": "CNA",
+      "url": "https://www.channelnewsasia.com/rssfeed/8395986",
+      "weight": 3
+    },
+    {
+      "name": "Mercopress",
+      "url": "https://en.mercopress.com/rss/",
+      "weight": 3
+    }
   ]
-}
+}