feat: add per-workout-type pace range and expected HR zone

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

backend/internal/store/workoutpaces_test.go

@@ -0,0 +1,45 @@
+package store
+
+import (
+	"context"
+	"testing"
+)
+
+func TestWorkoutTypePaces_SeededOnePerKindThenUpdate(t *testing.T) {
+	db := openTestDB(t)
+	ctx := context.Background()
+
+	all, err := db.ListWorkoutTypePaces(ctx)
+	if err != nil {
+		t.Fatalf("ListWorkoutTypePaces: %v", err)
+	}
+	if len(all) != 7 {
+		t.Fatalf("expected 7 seeded pace rows (one per taxonomy kind), got %d", len(all))
+	}
+	for _, p := range all {
+		if p.PaceMinSecPerKm != nil || p.PaceMaxSecPerKm != nil || p.ExpectedHRZone != nil {
+			t.Errorf("expected all-nil seeded pace row for kind %d, got %+v", p.WorkoutKindID, p)
+		}
+	}
+
+	target := all[0]
+	minPace, maxPace, zone := 330.0, 420.0, 2
+	target.PaceMinSecPerKm = &minPace
+	target.PaceMaxSecPerKm = &maxPace
+	target.ExpectedHRZone = &zone
+
+	if err := db.UpdateWorkoutTypePace(ctx, target); err != nil {
+		t.Fatalf("UpdateWorkoutTypePace: %v", err)
+	}
+
+	got, err := db.GetWorkoutTypePace(ctx, target.WorkoutKindID)
+	if err != nil {
+		t.Fatalf("GetWorkoutTypePace: %v", err)
+	}
+	if got.PaceMinSecPerKm == nil || *got.PaceMinSecPerKm != 330 {
+		t.Errorf("PaceMinSecPerKm = %v, want 330", got.PaceMinSecPerKm)
+	}
+	if got.ExpectedHRZone == nil || *got.ExpectedHRZone != 2 {
+		t.Errorf("ExpectedHRZone = %v, want 2", got.ExpectedHRZone)
+	}
+}