feat(time_entries): add time_entries app's basic structure and endpoints

apps/time_entries/api/serializers.py

@@ -0,0 +1,78 @@
+from rest_framework import serializers
+
+from core.serializers.base import BaseModelSerializer
+from apps.time_entries.models import TimeEntry
+from apps.projects.models import Project
+from apps.tags.models import Tag
+
+
+class TimeEntrySerializer(BaseModelSerializer):
+    """
+    Output serializer for TimeEntry.
+    """
+    class Meta:
+        model = TimeEntry
+        fields = BaseModelSerializer.Meta.fields + (
+            "workspace",
+            "user",
+            "project",
+            "description",
+            "start_time",
+            "end_time",
+            "duration",
+            "tags",
+            "is_billable",
+            "hourly_rate",
+            "currency",
+        )
+        read_only_fields = fields
+
+
+class TimeEntryCreateSerializer(serializers.Serializer):
+    """
+    Validates input data for creating/starting a time entry.
+    """
+    workspace_id = serializers.UUIDField()
+    project_id = serializers.PrimaryKeyRelatedField(
+        queryset=Project.objects.filter(is_deleted=False), 
+        required=False, 
+        allow_null=True, 
+        source='project'
+    )
+    start_time = serializers.DateTimeField()
+    end_time = serializers.DateTimeField(required=False, allow_null=True)
+    description = serializers.CharField(required=False, allow_blank=True, default="")
+    tags = serializers.PrimaryKeyRelatedField(
+        queryset=Tag.objects.filter(is_deleted=False), 
+        many=True, 
+        required=False
+    )
+    is_billable = serializers.BooleanField(default=False)
+
+
+class TimeEntryUpdateSerializer(serializers.Serializer):
+    """
+    Validates input data for updating an existing time entry.
+    """
+    project_id = serializers.PrimaryKeyRelatedField(
+        queryset=Project.objects.filter(is_deleted=False), 
+        required=False, 
+        allow_null=True, 
+        source='project'
+    )
+    start_time = serializers.DateTimeField(required=False)
+    end_time = serializers.DateTimeField(required=False, allow_null=True)
+    description = serializers.CharField(required=False, allow_blank=True)
+    tags = serializers.PrimaryKeyRelatedField(
+        queryset=Tag.objects.filter(is_deleted=False), 
+        many=True, 
+        required=False
+    )
+    is_billable = serializers.BooleanField(required=False)
+
+
+class TimeEntryStopSerializer(serializers.Serializer):
+    """
+    Optional specific serializer for stopping a timer manually.
+    """
+    end_time = serializers.DateTimeField(required=False, allow_null=True)