Phase 23: UI redesign — responsive mobile + desktop layout

- Replace SB Admin 2 sidebar with a clean fixed sidebar (desktop)
  and a sticky bottom tab navigation (mobile, ≤767px)
- Sidebar collapses to icon-only mode with state persisted in localStorage
- Logo is a functional home link on all viewports
- Mobile: full-width content, bottom nav replaces sidebar
- Dashboard: 6 OBD stat cards (status, speed, RPM, coolant, throttle, fuel)
  wired to live socket events; removed all placeholder buttons/dropdowns
- GPS info section cleaned up (lat/lon display instead of X/Y paragraphs)
- DTC page: live /api/dtc wiring — MIL indicator + DTC table populated from API
- New /api/dtc route added to app.py (mil + codes)
- yaris.js: added obd_coolant_temp / obd_fuel_level / obd_throttle listeners
- yaris.css: full rewrite — layout variables, sidebar, bottom nav, OBD cards,
  border-start utilities, mobile padding for bottom nav

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

static/js/yaris.js

@@ -94,6 +94,21 @@ socket.on('obd_rpm', function(data) {
     status.innerHTML = data;
 });
 
+socket.on('obd_coolant_temp', function(data) {
+    const el = document.getElementById('obd-coolant');
+    if (el) el.textContent = data != null ? data + ' °C' : '—';
+});
+
+socket.on('obd_fuel_level', function(data) {
+    const el = document.getElementById('obd-fuel');
+    if (el) el.textContent = data != null ? data + ' %' : '—';
+});
+
+socket.on('obd_throttle', function(data) {
+    const el = document.getElementById('obd-throttle');
+    if (el) el.textContent = data != null ? data + ' %' : '—';
+});
+
 socket.on('obd_error', function(data) {
     console.log("obd errors "+data);
     const status = document.getElementById('obd-error');