feat: add GPS trip detection, history panel, and playback (#23)

Auto-detect trips from GPS data (5-min idle threshold), pre-compute
OSRM routes on trip completion, add trip history side panel with
toggleable trips, and animated trip playback with speed controls.

- Add GpsTrip model with TripStatus enum and migration
- Trip detection in syncPositions cron (start on movement, end on idle)
- Trip finalization with OSRM route matching and stats computation
- API endpoints: list/detail/active/merge/backfill trips
- Stats tab overhaul: trip list panel + map with colored polylines
- Trip playback: animated marker, progressive trail, 1x-16x speed
- Live map shows active trip trail instead of full day history
- Historical backfill from existing GPS location data

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/prisma/migrations/20260208165115_add_gps_trips/migration.sql

@@ -0,0 +1,34 @@
+-- CreateEnum
+CREATE TYPE "TripStatus" AS ENUM ('ACTIVE', 'COMPLETED', 'PROCESSING', 'FAILED');
+
+-- CreateTable
+CREATE TABLE "gps_trips" (
+    "id" TEXT NOT NULL,
+    "deviceId" TEXT NOT NULL,
+    "status" "TripStatus" NOT NULL DEFAULT 'ACTIVE',
+    "startTime" TIMESTAMP(3) NOT NULL,
+    "endTime" TIMESTAMP(3),
+    "startLatitude" DOUBLE PRECISION NOT NULL,
+    "startLongitude" DOUBLE PRECISION NOT NULL,
+    "endLatitude" DOUBLE PRECISION,
+    "endLongitude" DOUBLE PRECISION,
+    "distanceMiles" DOUBLE PRECISION,
+    "durationSeconds" INTEGER,
+    "topSpeedMph" DOUBLE PRECISION,
+    "averageSpeedMph" DOUBLE PRECISION,
+    "pointCount" INTEGER NOT NULL DEFAULT 0,
+    "matchedRoute" JSONB,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "gps_trips_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "gps_trips_deviceId_startTime_idx" ON "gps_trips"("deviceId", "startTime");
+
+-- CreateIndex
+CREATE INDEX "gps_trips_status_idx" ON "gps_trips"("status");
+
+-- AddForeignKey
+ALTER TABLE "gps_trips" ADD CONSTRAINT "gps_trips_deviceId_fkey" FOREIGN KEY ("deviceId") REFERENCES "gps_devices"("id") ON DELETE CASCADE ON UPDATE CASCADE;