test: add scheduling excludeUserID integration test

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/handlers/scheduling/scheduling_test.go

@@ -2882,3 +2882,48 @@ func TestScheduling_DST_AutumnBack_BookingAt0130GMT(t *testing.T) {
 		t.Error("expected 01:30 GMT slot to be blocked (booking at 01:30 GMT = 01:30 UTC)")
 	}
 }
+
+// TestScheduling_GetAvailableHours_ExcludesOwnReservation verifies that an
+// authenticated user's own RESERVATION entry is excluded from time blockers
+// via the excludeUserID parameter in GetTimeBlockersInRange.
+func TestScheduling_GetAvailableHours_ExcludesOwnReservation(t *testing.T) {
+	ctx, tx := resetTestData(t)
+
+	userID, err := fixtures.CreateTestUser(tx)
+	if err != nil {
+		t.Fatalf("failed to create user: %v", err)
+	}
+
+	reservationTime := time.Date(2026, 3, 17, 10, 0, 0, 0, time.UTC)
+	_, err = tx.Exec(ctx, `
+		INSERT INTO time_blockers (start_time, duration_minutes, description, created_by)
+		VALUES ($1, 60, 'RESERVATION:user:' || $2 || ':' || EXTRACT(epoch FROM NOW())::bigint::text, $2)
+	`, reservationTime, userID)
+	if err != nil {
+		t.Fatalf("failed to create reservation: %v", err)
+	}
+
+	// Request available hours as THIS user — their own reservation should be excluded
+	handler := http.HandlerFunc(GetAvailableHours)
+	req := httptest.NewRequest("GET", "/api/scheduling/available-hours?start=2026-03-17&end=2026-03-17", nil)
+	reqCtx := context.WithValue(ctx, mw.UserIDKey, userID)
+	reqCtx = context.WithValue(reqCtx, mw.UserRoleKey, "verified_email")
+	req = req.WithContext(reqCtx)
+	w := httptest.NewRecorder()
+	handler.ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	var response []DayAvailableHours
+	json.Unmarshal(w.Body.Bytes(), &response)
+	targetDay := findDayByDate(response, "2026-03-17")
+	if targetDay == nil {
+		t.Fatal("expected 2026-03-17 in response")
+	}
+
+	// The user's own reservation at 10:00 should NOT block the slot
+	if !slotExists(targetDay.Slots, "10:00") {
+		t.Error("expected 10:00 to be available (own reservation excluded)")
+	}
+}