Improvements to node filtering and storage (#839)

* Improves node filtering and voltage display

Ensures voltage values are always displayed as positive.

Enhances node filtering logic to handle unknown or undefined values, preventing nodes from being unexpectedly hidden.

Updates UI labels for clarity.

Improves Nodes page responsiveness by debouncing node updates and optimizing selector usage, preventing unnecessary re-renders.

Adds validation warnings for key conflicts between nodes.

* Update packages/web/src/core/stores/nodeDBStore/nodeDBStore.test.tsx

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update packages/web/src/core/stores/nodeDBStore/nodeValidation.ts

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Revert copilot suggestion

* Review changes

---------

Co-authored-by: philon- <philon-@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

packages/web/public/i18n/locales/en/nodes.json

@@ -46,11 +46,7 @@
     "connectionStatus": {
       "direct": "Direct",
       "away": "away",
-      "unknown": "-",
       "viaMqtt": ", via MQTT"
-    },
-    "lastHeardStatus": {
-      "never": "Never"
     }
   },
 

packages/web/public/i18n/locales/en/ui.json

@@ -182,7 +182,7 @@
     "label": "Unknown number of hops"
   },
   "showUnheard": {
-    "label": "Never heard"
+    "label": "Unknown last heard"
   },
   "language": {
     "label": "Language",