feat(calendar): implement calendar event management with create, update, and delete functionalities

- Added actions for creating, updating, and deleting calendar events in `actions.ts`.
- Introduced `CalendarClient` component to handle event display and interaction in `calendar-client.tsx`.
- Refactored `CalendarPage` to fetch events, clients, projects, and tasks from Supabase and pass them to `CalendarClient`.
- Enhanced form handling for event creation and editing with proper validation and error handling.

app/(dashboard)/calendar/actions.ts

@@ -0,0 +1,106 @@
+"use server";
+
+import { createClient } from "@/lib/supabase/server";
+import { revalidatePath } from "next/cache";
+
+const EVENT_TYPES = ["meeting", "focus", "deadline", "personal", "finance"] as const;
+
+function cleanText(value: FormDataEntryValue | null) {
+  const text = typeof value === "string" ? value.trim() : "";
+  return text.length > 0 && text !== "__none" ? text : null;
+}
+
+function readType(value: FormDataEntryValue | null) {
+  const type = typeof value === "string" ? value : "focus";
+  return EVENT_TYPES.includes(type as (typeof EVENT_TYPES)[number]) ? type : "focus";
+}
+
+async function getCurrentUserId() {
+  const supabase = await createClient();
+  const {
+    data: { user },
+    error,
+  } = await supabase.auth.getUser();
+
+  if (error || !user) {
+    throw new Error("Takvim işlemi için giriş yapmış kullanıcı bulunamadı.");
+  }
+
+  return { supabase, userId: user.id };
+}
+
+function readPayload(formData: FormData) {
+  return {
+    title: cleanText(formData.get("title")),
+    description: cleanText(formData.get("description")),
+    type: readType(formData.get("type")),
+    starts_at: cleanText(formData.get("starts_at")),
+    ends_at: cleanText(formData.get("ends_at")),
+    client_id: cleanText(formData.get("client_id")),
+    project_id: cleanText(formData.get("project_id")),
+    task_id: cleanText(formData.get("task_id")),
+  };
+}
+
+export async function createCalendarEventRecord(formData: FormData) {
+  const { supabase, userId } = await getCurrentUserId();
+  const payload = readPayload(formData);
+
+  if (!payload.title || !payload.starts_at) {
+    throw new Error("Etkinlik başlığı ve başlangıç zamanı zorunludur.");
+  }
+
+  const { error } = await supabase.from("calendar_events").insert({
+    user_id: userId,
+    ...payload,
+  });
+
+  if (error) {
+    throw new Error(`Etkinlik eklenemedi: ${error.message}`);
+  }
+
+  revalidatePath("/calendar");
+}
+
+export async function updateCalendarEventRecord(formData: FormData) {
+  const { supabase, userId } = await getCurrentUserId();
+  const id = cleanText(formData.get("id"));
+  const payload = readPayload(formData);
+
+  if (!id || !payload.title || !payload.starts_at) {
+    throw new Error("Etkinlik güncellemek için başlık, başlangıç ve kayıt kimliği zorunludur.");
+  }
+
+  const { error } = await supabase
+    .from("calendar_events")
+    .update(payload)
+    .eq("id", id)
+    .eq("user_id", userId);
+
+  if (error) {
+    throw new Error(`Etkinlik güncellenemedi: ${error.message}`);
+  }
+
+  revalidatePath("/calendar");
+}
+
+export async function deleteCalendarEventRecord(formData: FormData) {
+  const { supabase, userId } = await getCurrentUserId();
+  const id = cleanText(formData.get("id"));
+
+  if (!id) {
+    throw new Error("Silinecek etkinlik bulunamadı.");
+  }
+
+  const { error } = await supabase
+    .from("calendar_events")
+    .delete()
+    .eq("id", id)
+    .eq("user_id", userId);
+
+  if (error) {
+    throw new Error(`Etkinlik silinemedi: ${error.message}`);
+  }
+
+  revalidatePath("/calendar");
+}