Add comprehensive tests for scheduled task repository, scheduler service, and task handlers

- Implemented tests for ScheduledTaskRepository covering task creation, retrieval, filtering, and status updates.
- Developed tests for SchedulerService including task creation, cancellation, user task retrieval, and maintenance jobs.
- Created tests for TaskHandlerRegistry to validate task execution for various types, including credit recharge and sound playback.
- Ensured proper error handling and edge cases in task execution scenarios.
- Added fixtures and mocks to facilitate isolated testing of services and repositories.

uv.lock

@@ -742,6 +742,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/5b/ee/7d76eb3b50ccb1397621f32ede0fb4d17aa55a9aa2251bc34e6b9929fdce/python_vlc-3.0.21203-py3-none-any.whl", hash = "sha256:1613451a31b692ec276296ceeae0c0ba82bfc2d094dabf9aceb70f58944a6320", size = 87651 },
 ]
 
+[[package]]
+name = "pytz"
+version = "2024.1"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/90/26/9f1f00a5d021fff16dee3de13d43e5e978f3d58928e129c3a62cf7eb9738/pytz-2024.1.tar.gz", hash = "sha256:2a29735ea9c18baf14b448846bde5a48030ed267578472d8955cd0e7443a9812", size = 316214 }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/9c/3d/a121f284241f08268b21359bd425f7d4825cffc5ac5cd0e1b3d82ffd2b10/pytz-2024.1-py2.py3-none-any.whl", hash = "sha256:328171f4e3623139da4983451950b28e95ac706e13f3f2630a879749e7a8b319", size = 505474 },
+]
+
 [[package]]
 name = "pyyaml"
 version = "6.0.2"
@@ -883,6 +892,7 @@ dependencies = [
     { name = "pyjwt" },
     { name = "python-socketio" },
     { name = "python-vlc" },
+    { name = "pytz" },
     { name = "sqlmodel" },
     { name = "uvicorn", extra = ["standard"] },
     { name = "yt-dlp" },
@@ -912,6 +922,7 @@ requires-dist = [
     { name = "pyjwt", specifier = "==2.10.1" },
     { name = "python-socketio", specifier = "==5.13.0" },
     { name = "python-vlc", specifier = "==3.0.21203" },
+    { name = "pytz", specifier = "==2024.1" },
     { name = "sqlmodel", specifier = "==0.0.24" },
     { name = "uvicorn", extras = ["standard"], specifier = "==0.35.0" },
     { name = "yt-dlp", specifier = "==2025.8.20" },