Phase 03: CAM decode coverage, real sensor data in TX, V2X monitor for ESP32 path

CAM codec:
- Stop rejecting CAMs carrying a specialVehicleContainer. It is declared last in
  CamParameters, after everything this decoder reads, so buses / emergency
  vehicles / road-works vehicles now decode for position and kinematics instead
  of being dropped outright
- Drop the lowFrequencyContainer parse - it extracted nothing into Cam, and its
  reads were only correct when no high-frequency optionals were present
- Document why the 7 optional-presence bits are consumed but not acted on: UPER
  writes a SEQUENCE's presence bitmap up front but each field's value in
  declaration order, and all seven are declared after yawRate
- Field widths and container ordering verified against the ETSI ASN.1 sources in
  the C-ITS-Parser checkout, not from memory

Transmit path:
- Own StationID is now a persisted random 32-bit value instead of a hardcoded 0.
  Receivers key on StationID to track a station across CAMs, so every unit
  broadcasting 0 made two MicrOBUs indistinguishable - including to this app's
  own detection engine
- Populate longitudinalAcceleration from successive GNSS speed samples. Not from
  the accelerometer: CAM wants signed along-track acceleration, and the raw
  sensor is device-frame with gravity in it. Null outside a usable sample gap
  rather than a fabricated value
- CAM pinger builds from live GNSS/IMU via PhoneCamBuilder instead of beaconing a
  hardcoded bench coordinate with speed and heading pinned to zero, so it now
  exercises the sensor pipeline and not just the wire. Sends nothing without a
  fix, and reports that rather than sitting at "Sent: 0"

V2X monitor:
- Received-CAM pane for the ESP32-C5 path, replacing the MQTT topic list that is
  permanently empty there. One row per station rather than per message - CAMs
  arrive at 1-10 Hz per station, so the pane is bounded by road users nearby, not
  by traffic rate. Nearest first, tinted by active alert level
- DENM hazard pins on the live map as a warning triangle, drawn above vehicle
  markers. CiT One path only: the ESP32 firmware forwards BTP-B port 2001 (CAM)
  and drops port 2002 before it reaches the phone

DenmParser uses tolerant field-name matching - the Use Case API's DENM JSON
schema is not yet confirmed against real payloads.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

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

@@ -204,7 +204,30 @@
 
     <!-- CAM-Pinger — nur ESP32-C5, manueller Bank-Test, Gegenstück zur DENM-TX-Karte oben -->
     <string name="mqtt_cam_pinger_title">CAM-Pinger (manueller Test)</string>
-    <string name="mqtt_cam_pinger_desc">Fester Standort, 1-Hz-CAM-Ping — prüft die serielle Verbindung und den ESP32-Funkpfad ohne GNSS-Bewegung oder Fahrtaufzeichnung.</string>
+    <string name="mqtt_cam_pinger_desc">1-Hz-CAM-Ping aus Live-GNSS- und IMU-Daten — prüft die serielle Verbindung und den ESP32-Funkpfad ohne Fahrtaufzeichnung.</string>
+    <string name="mqtt_cam_pinger_no_fix">Warte auf GNSS-Fix — noch nichts gesendet</string>
+
+    <!-- Empfangene CAMs (ESP32-C5-Pfad) -->
+    <string name="v2x_cam_rx_count">%1$d Station(en) in Reichweite — jeweils neueste CAM</string>
+    <string name="v2x_cam_rx_none">Keine CAMs empfangen</string>
+    <string name="v2x_cam_rx_none_hint">Dekodierte CAMs benachbarter Stationen erscheinen hier, sobald sie über die serielle Verbindung eintreffen.</string>
+    <string name="v2x_cam_rx_station">Station %1$d · %2$s</string>
+    <string name="v2x_cam_rx_kinematics">%1$.1f km/h · Kurs %2$.0f°</string>
+    <string name="v2x_cam_rx_distance">%1$.0f m</string>
+    <string name="v2x_cam_rx_distance_unknown">— m</string>
+
+    <!-- DENM-Kartenmarker -->
+    <string name="v2x_map_denm_labeled">Gefahr: Ursache %1$d/%2$d (Station %3$d)</string>
+    <string name="v2x_map_denm_plain">Gefahr von Station %1$d</string>
+
+    <!-- ETSI-Stationstypen -->
+    <string name="station_type_pedestrian">Fußgänger</string>
+    <string name="station_type_cyclist">Radfahrer</string>
+    <string name="station_type_car">Pkw</string>
+    <string name="station_type_bus">Bus</string>
+    <string name="station_type_truck">Lkw</string>
+    <string name="station_type_rsu">Straßenseiteneinheit</string>
+    <string name="station_type_other">Typ %1$d</string>
     <string name="mqtt_cam_pinger_not_connected">ESP32-C5 verbinden, um den CAM-Pinger zu aktivieren</string>
     <string name="mqtt_cam_pinger_active">Sendet — 1 CAM/s über die serielle Verbindung</string>
     <string name="mqtt_cam_pinger_sent_count">Gesendet: %1$d</string>