refactor(clients): reorganize client modules into clients package

- Move auth, user, and music clients into new clients package
- Update imports to use new module paths
- Add __init__.py to expose clients from package
- Clean up code formatting and imports
- Add pre-commit configuration for code quality checks

.pre-commit-config.yaml

@@ -0,0 +1,35 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.5.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-merge-conflict
+      - id: check-added-large-files
+      - id: check-ast
+      - id: check-case-conflict
+      - id: check-executables-have-shebangs
+      - id: check-json
+      - id: check-merge-conflict
+      - id: check-symlinks
+      - id: detect-private-key
+      - id: file-contents-sorter
+      - id: mixed-line-ending
+      - id: name-tests-test
+      - id: pretty-format-json
+        args: [--autofix]
+      - id: debug-statements
+      - id: check-docstring-first
+      - id: requirements-txt-fixer
+
+  - repo: https://github.com/psf/black
+    rev: 24.2.0
+    hooks:
+      - id: black
+        language_version: python3
+
+  - repo: https://github.com/PyCQA/isort
+    rev: 6.0.1
+    hooks:
+      - id: isort
+        args: ["--profile", "black"]