fitness: add GPX upload with map, pace chart, and km splits

Add GPX file upload for cardio exercises in workout history. Parses
GPX track points and stores them in the session. Shows route map
(Leaflet), pace-over-distance chart (Chart.js), and per-km splits
table with color-coded fast/slow pacing. Auto-fills distance and
duration on single-set exercises. Disables Chart.js animations.

src/models/WorkoutSession.ts

@@ -10,12 +10,22 @@ export interface ICompletedSet {
   notes?: string;
 }
 
+export interface IGpsPoint {
+  lat: number;
+  lng: number;
+  altitude?: number;
+  speed?: number;
+  timestamp: number;
+}
+
 export interface ICompletedExercise {
   exerciseId: string;
   name: string;
   sets: ICompletedSet[];
   restTime?: number;
   notes?: string;
+  gpsTrack?: IGpsPoint[];
+  totalDistance?: number; // km
 }
 
 export interface IWorkoutSession {
@@ -70,6 +80,14 @@ const CompletedSetSchema = new mongoose.Schema({
   }
 });
 
+const GpsPointSchema = new mongoose.Schema({
+  lat: { type: Number, required: true },
+  lng: { type: Number, required: true },
+  altitude: Number,
+  speed: Number,
+  timestamp: { type: Number, required: true }
+}, { _id: false });
+
 const CompletedExerciseSchema = new mongoose.Schema({
   exerciseId: {
     type: String,
@@ -95,6 +113,14 @@ const CompletedExerciseSchema = new mongoose.Schema({
     type: String,
     trim: true,
     maxlength: 500
+  },
+  gpsTrack: {
+    type: [GpsPointSchema],
+    default: undefined
+  },
+  totalDistance: {
+    type: Number,
+    min: 0
   }
 });
 
@@ -157,4 +183,4 @@ const WorkoutSessionSchema = new mongoose.Schema(
 WorkoutSessionSchema.index({ createdBy: 1, startTime: -1 });
 WorkoutSessionSchema.index({ templateId: 1 });
 
-export const WorkoutSession = mongoose.model<IWorkoutSession>("WorkoutSession", WorkoutSessionSchema);
+export const WorkoutSession = mongoose.models.WorkoutSession as mongoose.Model<IWorkoutSession> ?? mongoose.model<IWorkoutSession>("WorkoutSession", WorkoutSessionSchema);