feat: flexible group management in schedule editor

- Group = trainer + type (time-independent)
- Edit modal shows per-day time fields (Mon 12:00, Fri 18:00)
- Calendar blocks colored by group, not class type
- Color picker for site dots moved to classes editor
- New class: single time + multi-day selector
- Edit class: per-day times, add/remove days from group
- Delete removes group from all days

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

src/app/admin/classes/page.tsx

@@ -9,6 +9,25 @@ const ICON_OPTIONS = [
   "heart", "music", "dumbbell", "trophy",
 ];
 
+const COLOR_SWATCHES: { value: string; bg: string }[] = [
+  { value: "rose", bg: "bg-rose-500" },
+  { value: "orange", bg: "bg-orange-500" },
+  { value: "amber", bg: "bg-amber-500" },
+  { value: "yellow", bg: "bg-yellow-400" },
+  { value: "lime", bg: "bg-lime-500" },
+  { value: "emerald", bg: "bg-emerald-500" },
+  { value: "teal", bg: "bg-teal-500" },
+  { value: "cyan", bg: "bg-cyan-500" },
+  { value: "sky", bg: "bg-sky-500" },
+  { value: "blue", bg: "bg-blue-500" },
+  { value: "indigo", bg: "bg-indigo-500" },
+  { value: "violet", bg: "bg-violet-500" },
+  { value: "purple", bg: "bg-purple-500" },
+  { value: "fuchsia", bg: "bg-fuchsia-500" },
+  { value: "pink", bg: "bg-pink-500" },
+  { value: "red", bg: "bg-red-500" },
+];
+
 interface ClassesData {
   title: string;
   items: {
@@ -63,6 +82,31 @@ export default function ClassesEditorPage() {
                     </select>
                   </div>
                 </div>
+                <div>
+                  <label className="block text-sm text-neutral-400 mb-1.5">
+                    Цвет в расписании
+                  </label>
+                  <div className="flex flex-wrap gap-1.5">
+                    {COLOR_SWATCHES.map((c) => {
+                      const isUsed = data.items.some(
+                        (other) => other !== item && other.color === c.value
+                      );
+                      if (isUsed) return null;
+                      return (
+                        <button
+                          key={c.value}
+                          type="button"
+                          onClick={() => updateItem({ ...item, color: c.value })}
+                          className={`h-6 w-6 rounded-full ${c.bg} transition-all ${
+                            item.color === c.value
+                              ? "ring-2 ring-white ring-offset-1 ring-offset-neutral-900 scale-110"
+                              : "opacity-50 hover:opacity-100"
+                          }`}
+                        />
+                      );
+                    })}
+                  </div>
+                </div>
                 <TextareaField
                   label="Краткое описание"
                   value={item.description}