Dashboard: surface the nearest hazard and the next signal change

Two cards below the status cards, each shown only when there is
something to show and each opening the V2X screen when tapped.

Hazard: cause name, distance, and a count of the others behind it,
ranked closest first. A hazard whose distance cannot be resolved,
because there is no fix yet, sorts last rather than being dropped.

Traffic light: the intersection changing soonest, its leading phase
with a countdown, and every signal group as a colour-coded chip. The
countdown runs on its own 500 ms clock rather than on SPATEM arrivals,
so it cannot freeze mid-count and keep claiming a light is about to
change after the RSU stops transmitting.

Signals are ranked by time-to-change rather than by distance because
SPATEM carries no position at all. Placing an intersection needs MAPEM
geometry, which nothing on air is currently sending.

Also fixes bottom-nav taps. One rule now applies to every tab: a tap
lands on that tab's own screen, popping back to it when it is still on
the stack so the gesture behaves exactly like Back or a back swipe.
saveState/restoreState are gone, since on this flat graph a restored
back stack brought back the sub-screen the rider was on instead of the
tab root, which is the opposite of what the tap asked for. Tabs also
now stay lit on the screens that belong to them.

app/src/main/res/values/strings.xml

@@ -32,6 +32,19 @@
     <string name="dash_samples">samples</string>
     <string name="dash_start_driving_session">Start Driving Session</string>
     <string name="dash_initialising">Initialising…</string>
+
+    <!-- Dashboard live V2X panel: nearest hazard and nearest signalised intersection -->
+    <string name="dash_hazard_warning">Hazard warning</string>
+    <string name="dash_hazard_station">station %1$d</string>
+    <string name="dash_more_count">+%1$d more</string>
+    <string name="dash_signal_title">Traffic light %1$s</string>
+    <string name="dash_signal_more">+%1$d more intersection(s)</string>
+    <string name="dash_signal_phase_go">Green</string>
+    <string name="dash_signal_phase_stop">Red</string>
+    <string name="dash_signal_phase_changing">Changing</string>
+    <string name="dash_signal_phase_dark">Dark</string>
+    <string name="dash_signal_phase_unknown">Unknown</string>
+    <string name="dash_signal_countdown">%1$s · %2$.0f s</string>
     <string name="stat_pressure">Pressure</string>
     <string name="stat_altitude">Altitude</string>
     <string name="stat_heading">Heading</string>