Add a Charging tab to the web app sidebar

Mirror the web-dashboard UI kit's charging screen: a map panel with
charger pins, an active-session card, and a nearby-stations list. Adds
the sidebar nav item, the /charging route, and the Charging view, plus
en/pl/da translations. Session and station data are presentational
placeholders until the server exposes charging telemetry.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Web App/web/src/i18n/en.json

@@ -23,6 +23,7 @@
 
   "nav": {
     "garage": "Garage",
+    "charging": "Charging",
     "settings": "Settings",
     "users": "Users",
     "lightMode": "Light mode",
@@ -31,6 +32,34 @@
     "logOut": "Log out"
   },
 
+  "charging": {
+    "eyebrow": "Charging & map",
+    "title": "Nearby chargers",
+    "liveMap": "Live map",
+    "youAreHere": "You are here",
+    "session": {
+      "chargingNow": "Charging now",
+      "rate": "Rate",
+      "added": "Added",
+      "cost": "Cost",
+      "done": "Done",
+      "stop": "Stop charging",
+      "idle": "Not charging",
+      "idleHint": "Plug in at a station to start a session."
+    },
+    "stations": {
+      "heading": "Nearby",
+      "count": {
+        "one": "{n} station",
+        "other": "{n} stations"
+      },
+      "free": "{avail} of {total} free",
+      "full": "Full",
+      "offPeak": "off-peak",
+      "homeCharger": "Home charger"
+    }
+  },
+
   "login": {
     "title": "Sign in",
     "tagline": "Your car, on track.",