fix(calendar) #263 : calculate dynamic week range for month view data loading (#264)

- Calculate exact number of weeks needed instead of fixed 6 weeks
- Compute weeks based on actual days from startDate to lastOfMonth

__test__/utils/dateUtils.test.ts

@@ -0,0 +1,38 @@
+import { getCalendarRange } from "../../src/utils/dateUtils";
+
+describe("getCalendarRange", () => {
+  it("Nov 2025 (5 weeks): 2025-10-27 to 2025-11-30", () => {
+    const { start, end } = getCalendarRange(
+      new Date("2025-11-01T00:00:00.000Z")
+    );
+    expect(start.toISOString().slice(0, 10)).toBe("2025-10-27");
+    expect(end.toISOString().slice(0, 10)).toBe("2025-11-30");
+  });
+
+  it("Dec 2025 (6 weeks): end Sunday 2026-01-04", () => {
+    const { start, end } = getCalendarRange(
+      new Date("2025-12-01T00:00:00.000Z")
+    );
+    expect(start.toISOString().slice(0, 10)).toBe("2025-12-01");
+    expect(end.toISOString().slice(0, 10)).toBe("2026-01-04");
+  });
+
+  it("Feb 2025 (short month): end Sunday 2025-03-02", () => {
+    const { start, end } = getCalendarRange(
+      new Date("2025-02-01T00:00:00.000Z")
+    );
+    expect(start.toISOString().slice(0, 10)).toBe("2025-01-27");
+    expect(end.toISOString().slice(0, 10)).toBe("2025-03-02");
+  });
+
+  it("sets boundary times correctly (start 00:00, end 23:59)", () => {
+    const { start, end } = getCalendarRange(
+      new Date("2025-11-01T00:00:00.000Z")
+    );
+    expect(start.getHours()).toBe(0);
+    expect(start.getMinutes()).toBe(0);
+    expect(start.getSeconds()).toBe(0);
+    expect(end.getHours()).toBe(23);
+    expect(end.getMinutes()).toBe(59);
+  });
+});