refactor: remove Redis dependency and related code

backend/uv.lock

@@ -1124,15 +1124,6 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/f1/12/de94a39c2ef588c7e6455cfbe7343d3b2dc9d6b6b2f40c4c6565744c873d/pyyaml-6.0.3-cp314-cp314t-win_arm64.whl", hash = "sha256:ebc55a14a21cb14062aa4162f906cd962b28e2e9ea38f9b4391244cd8de4ae0b", size = 149341, upload-time = "2025-09-25T21:32:56.828Z" },
 ]
 
-[[package]]
-name = "redis"
-version = "7.4.0"
-source = { registry = "https://pypi.org/simple" }
-sdist = { url = "https://files.pythonhosted.org/packages/7b/7f/3759b1d0d72b7c92f0d70ffd9dc962b7b7b5ee74e135f9d7d8ab06b8a318/redis-7.4.0.tar.gz", hash = "sha256:64a6ea7bf567ad43c964d2c30d82853f8df927c5c9017766c55a1d1ed95d18ad", size = 4943913, upload-time = "2026-03-24T09:14:37.53Z" }
-wheels = [
-    { url = "https://files.pythonhosted.org/packages/74/3a/95deec7db1eb53979973ebd156f3369a72732208d1391cd2e5d127062a32/redis-7.4.0-py3-none-any.whl", hash = "sha256:a9c74a5c893a5ef8455a5adb793a31bb70feb821c86eccb62eebef5a19c429ec", size = 409772, upload-time = "2026-03-24T09:14:35.968Z" },
-]
-
 [[package]]
 name = "rich"
 version = "15.0.0"
@@ -1304,7 +1295,6 @@ dependencies = [
     { name = "pydantic" },
     { name = "pydantic-settings" },
     { name = "pyyaml" },
-    { name = "redis" },
     { name = "ruff" },
 ]
 
@@ -1324,7 +1314,6 @@ requires-dist = [
     { name = "pydantic", specifier = ">=2.12.5" },
     { name = "pydantic-settings", specifier = ">=2.13.1" },
     { name = "pyyaml", specifier = ">=6.0.3" },
-    { name = "redis", specifier = ">=7.4.0" },
     { name = "ruff", specifier = ">=0.15.10" },
 ]