feat: 添加日历批量操作与客户端时区感知功能，优化前端 UI 交互体验

backend/tests/unit/v1/schedule_items/test_schemas.py

@@ -16,6 +16,7 @@ def test_create_request_valid() -> None:
     request = ScheduleItemCreateRequest(
         title="Test Event",
         start_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
+        timezone="UTC",
     )
     assert request.title == "Test Event"
     assert request.timezone == "UTC"
@@ -26,6 +27,7 @@ def test_create_request_with_end_at() -> None:
         title="Test Event",
         start_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
         end_at=datetime(2026, 2, 28, 17, 30, 0, tzinfo=timezone.utc),
+        timezone="UTC",
     )
     assert request.end_at is not None
 
@@ -35,6 +37,7 @@ def test_create_request_invalid_title_empty() -> None:
         ScheduleItemCreateRequest(
             title="",
             start_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
+            timezone="UTC",
         )
 
 
@@ -43,6 +46,7 @@ def test_create_request_invalid_title_too_long() -> None:
         ScheduleItemCreateRequest(
             title="x" * 256,
             start_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
+            timezone="UTC",
         )
 
 
@@ -56,6 +60,7 @@ def test_create_request_with_metadata() -> None:
     request = ScheduleItemCreateRequest(
         title="Test Event",
         start_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
+        timezone="UTC",
         metadata=metadata,
     )
     assert request.metadata is not None
@@ -68,6 +73,24 @@ def test_update_request_partial() -> None:
     assert request.description is None
 
 
+def test_create_request_rejects_naive_datetime() -> None:
+    with pytest.raises(ValidationError):
+        ScheduleItemCreateRequest(
+            title="Test Event",
+            start_at=datetime(2026, 2, 28, 16, 0, 0),
+            timezone="UTC",
+        )
+
+
+def test_create_request_rejects_invalid_timezone() -> None:
+    with pytest.raises(ValidationError):
+        ScheduleItemCreateRequest(
+            title="Test Event",
+            start_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
+            timezone="Mars/OlympusMons",
+        )
+
+
 def test_metadata_attachment_document() -> None:
     attachment = ScheduleItemMetadataAttachment(
         name="document.pdf",
@@ -95,7 +118,7 @@ def test_metadata_rejects_invalid_color() -> None:
 
 def test_metadata_rejects_invalid_version() -> None:
     with pytest.raises(ValidationError):
-        ScheduleItemMetadata(version=2)
+        ScheduleItemMetadata.model_validate({"version": 2})
 
 
 def test_metadata_rejects_unknown_field() -> None:

backend/tests/unit/v1/schedule_items/test_service.py

@@ -148,6 +148,7 @@ async def test_create_success(
     request = ScheduleItemCreateRequest(
         title="Test Event",
         start_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
+        timezone="UTC",
     )
     service = ScheduleItemService(
         repository=FakeRepo(None),
@@ -171,6 +172,7 @@ async def test_create_invalid_end_at(
         title="Test Event",
         start_at=datetime(2026, 2, 28, 17, 0, 0, tzinfo=timezone.utc),
         end_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
+        timezone="UTC",
     )
     service = ScheduleItemService(
         repository=FakeRepo(None),
@@ -275,6 +277,7 @@ async def test_create_maps_metadata_to_extra_metadata(
     request = ScheduleItemCreateRequest(
         title="Roadmap",
         start_at=datetime(2026, 2, 28, 16, 0, 0, tzinfo=timezone.utc),
+        timezone="UTC",
         metadata=ScheduleItemMetadata(
             location="会议室A",
             color="#4F46E5",