Add Raspberry Pi health monitoring

Co-authored-by: Copilot <[email protected]>

readme.md

@@ -57,6 +57,8 @@ i have a dream
   WiFi/Ethernet is unavailable (dashcam video stays off cellular)
 - 🗄️ **Motion-aware local-first SQLite logging** — five-second motion checks without five-second
   parked writes, plus retry-safe remote sync and automatic backoff
+- 🌡️ **Pi health monitoring** — dashboard temperature, RAM, disk space, uptime, and explicit
+  undervoltage/throttling warnings from the Raspberry Pi firmware
 - 🛣️ **Trip history and route replay** — detects motion from OBD wheel speed with sustained GPS
   displacement as a fallback, summarizes distance and speed in metric/imperial units, and replays
   each route as a line on the offline map with a timestamped play/pause timeline and moving marker
@@ -96,7 +98,7 @@ For the remote server (receives trip logs + dashcam uploads), see [server/README
 
 ## Project status
 
-This project was revived after a couple of years on the shelf. Phases 1-13 and 15-18 are complete:
+This project was revived after a couple of years on the shelf. Phases 1-13 and 15-19 are complete:
 real GNSS, hardened OBD support, offline maps/UI, automatic WiFi hotspot switching, local logging,
 dashcam import, resumable remote upload, trip history/replay, deployment, and the shared UI
 foundation are implemented.
@@ -109,6 +111,6 @@ partition, and clean shutdown still needs delayed-power or ignition-sense hardwa
 
 The browser-based phone relay was removed after real-world testing confirmed that mobile browsers
 cannot reliably use the Pi's WiFi and cellular data simultaneously. A native Android companion is
-planned later instead. The next roadmap work is Pi health, followed by alerts, settings, and a
-final UI polish pass. Full phase history, verification notes, and current scope live in
+planned later instead. The next roadmap work is alerts, followed by settings and a final UI polish
+pass. Full phase history, verification notes, and current scope live in
 [PLAN.md](./PLAN.md).