Fix: SQLite integer 0 rendering as text, NaN avg response display

- maintenance_mode and hasActiveIncident are SQLite integers (0/1), not JS booleans.
  {0 && <span>} evaluates to {0} which React renders as the text "0" in the DOM.
  Fixed with !! coercion on both conditions in renderResourceRow.

- avgResponseTime can be NaN for resources with no checks (e.g. icmp with no data).
  Added || 0 guard in the aggregate average and —/ms conditional in the row display.

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

client/build/asset-manifest.json

@@ -1,15 +1,15 @@
 {
   "files": {
     "main.css": "/static/css/main.67d2dbc4.css",
-    "main.js": "/static/js/main.85e69234.js",
+    "main.js": "/static/js/main.1e7808e0.js",
     "static/js/453.d456ce70.chunk.js": "/static/js/453.d456ce70.chunk.js",
     "index.html": "/index.html",
     "main.67d2dbc4.css.map": "/static/css/main.67d2dbc4.css.map",
-    "main.85e69234.js.map": "/static/js/main.85e69234.js.map",
+    "main.1e7808e0.js.map": "/static/js/main.1e7808e0.js.map",
     "453.d456ce70.chunk.js.map": "/static/js/453.d456ce70.chunk.js.map"
   },
   "entrypoints": [
     "static/css/main.67d2dbc4.css",
-    "static/js/main.85e69234.js"
+    "static/js/main.1e7808e0.js"
   ]
 }