refactor: extract focused clients from GiteaClient (Slices 1-6)

- Create gitea/issues_client.py with IssuesClient class (9 methods)
- Create gitea/prs_client.py with PullRequestsClient class (17 methods)
- Create gitea/files_client.py with FilesClient class (4 methods)
- Create gitea/notifications_client.py with NotificationsClient class (2 methods)
- Create gitea/repos_client.py with ReposClient class (2 methods)
- Create gitea/__init__.py to export all client classes
- Remove delegation methods from GiteaClient (now ~70 lines)
- Update all callers to use sub-clients (client.issues, client.prs, etc.)
- Update test files to mock sub-client attributes

GiteaClient is now a facade that provides access to focused sub-clients:
- repos: Repository operations (ReposClient)
- issues: Issue operations (IssuesClient)
- prs: Pull request operations (PullRequestsClient)
- files: File and git ref operations (FilesClient)
- notifications: Notification operations (NotificationsClient)

Refs: #godclass-refactor

tests/test_file_tools.py

@@ -3,19 +3,28 @@ from gitea.client import GiteaClient
 from gitea.tools.file_tools import FileTools
 
 
-def test_get_file_content_string_success() -> None:
+def _create_mock_client() -> MagicMock:
+    """Create a mock GiteaClient with sub-client attributes."""
     mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.get_file_content.return_value = "file content here"
+    mock_client.files = MagicMock()
+    return mock_client
+
+
+def test_get_file_content_string_success() -> None:
+    mock_client = _create_mock_client()
+    mock_client.files.get_file_content.return_value = "file content here"
 
     file_tools: FileTools = FileTools(mock_client)
     res: str = file_tools.get_file_content("owner", "repo", "path/to/file")
     assert res == "1: file content here"
-    mock_client.get_file_content.assert_called_once_with("owner", "repo", "path/to/file")
+    mock_client.files.get_file_content.assert_called_once_with(
+        "owner", "repo", "path/to/file"
+    )
 
 
 def test_get_file_content_list_success() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.get_file_content.return_value = ["line1", "line2"]
+    mock_client = _create_mock_client()
+    mock_client.files.get_file_content.return_value = ["line1", "line2"]
 
     file_tools: FileTools = FileTools(mock_client)
     res: str = file_tools.get_file_content("owner", "repo", "path/to/file")
@@ -23,8 +32,8 @@ def test_get_file_content_list_success() -> None:
 
 
 def test_get_file_content_failure() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.get_file_content.side_effect = Exception("API Error")
+    mock_client = _create_mock_client()
+    mock_client.files.get_file_content.side_effect = Exception("API Error")
 
     file_tools: FileTools = FileTools(mock_client)
     res: str = file_tools.get_file_content("owner", "repo", "path/to/file")
@@ -32,66 +41,86 @@ def test_get_file_content_failure() -> None:
 
 
 def test_get_file_content_with_ref_string_success() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.get_file_content.return_value = "file content here"
+    mock_client = _create_mock_client()
+    mock_client.files.get_file_content.return_value = "file content here"
 
     file_tools: FileTools = FileTools(mock_client)
-    res: str = file_tools.get_file_content_with_ref("owner", "repo", "path/to/file", "main")
+    res: str = file_tools.get_file_content_with_ref(
+        "owner", "repo", "path/to/file", "main"
+    )
     assert res == "1: file content here"
-    mock_client.get_file_content.assert_called_once_with("owner", "repo", "path/to/file", "main")
+    mock_client.files.get_file_content.assert_called_once_with(
+        "owner", "repo", "path/to/file", "main"
+    )
 
 
 def test_get_file_content_with_ref_list_success() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.get_file_content.return_value = ["line1", "line2"]
+    mock_client = _create_mock_client()
+    mock_client.files.get_file_content.return_value = ["line1", "line2"]
 
     file_tools: FileTools = FileTools(mock_client)
-    res: str = file_tools.get_file_content_with_ref("owner", "repo", "path/to/file", "main")
+    res: str = file_tools.get_file_content_with_ref(
+        "owner", "repo", "path/to/file", "main"
+    )
     assert res == "1: line1\n2: line2"
 
 
 def test_get_file_content_with_ref_failure() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.get_file_content.side_effect = Exception("API Error")
+    mock_client = _create_mock_client()
+    mock_client.files.get_file_content.side_effect = Exception("API Error")
 
     file_tools: FileTools = FileTools(mock_client)
-    res: str = file_tools.get_file_content_with_ref("owner", "repo", "path/to/file", "main")
+    res: str = file_tools.get_file_content_with_ref(
+        "owner", "repo", "path/to/file", "main"
+    )
     assert "Error getting file content: API Error" in res
 
 
 def test_commit_file_success() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.update_file.return_value = {}
+    mock_client = _create_mock_client()
+    mock_client.files.update_file.return_value = {}
 
     file_tools: FileTools = FileTools(mock_client)
-    res: str = file_tools.commit_file("owner", "repo", "path/to/file", "msg", "content", "branch")
+    res: str = file_tools.commit_file(
+        "owner", "repo", "path/to/file", "msg", "content", "branch"
+    )
     assert "committed successfully" in res
-    mock_client.update_file.assert_called_once_with("owner", "repo", "path/to/file", "msg", "content", "branch")
+    mock_client.files.update_file.assert_called_once_with(
+        "owner", "repo", "path/to/file", "msg", "content", "branch"
+    )
 
 
 def test_commit_file_failure() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.update_file.side_effect = Exception("API Error")
+    mock_client = _create_mock_client()
+    mock_client.files.update_file.side_effect = Exception("API Error")
 
     file_tools: FileTools = FileTools(mock_client)
-    res: str = file_tools.commit_file("owner", "repo", "path/to/file", "msg", "content", "branch")
+    res: str = file_tools.commit_file(
+        "owner", "repo", "path/to/file", "msg", "content", "branch"
+    )
     assert "Error committing file: API Error" in res
 
 
 def test_update_file_success() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.update_file.return_value = {}
+    mock_client = _create_mock_client()
+    mock_client.files.update_file.return_value = {}
 
     file_tools: FileTools = FileTools(mock_client)
-    res: str = file_tools.update_file("owner", "repo", "path/to/file", "msg", "content", "branch")
+    res: str = file_tools.update_file(
+        "owner", "repo", "path/to/file", "msg", "content", "branch"
+    )
     assert "updated in" in res
-    mock_client.update_file.assert_called_once_with("owner", "repo", "path/to/file", "msg", "content", "branch")
+    mock_client.files.update_file.assert_called_once_with(
+        "owner", "repo", "path/to/file", "msg", "content", "branch"
+    )
 
 
 def test_update_file_failure() -> None:
-    mock_client: MagicMock = MagicMock(spec=GiteaClient)
-    mock_client.update_file.side_effect = Exception("API Error")
+    mock_client = _create_mock_client()
+    mock_client.files.update_file.side_effect = Exception("API Error")
 
     file_tools: FileTools = FileTools(mock_client)
-    res: str = file_tools.update_file("owner", "repo", "path/to/file", "msg", "content", "branch")
+    res: str = file_tools.update_file(
+        "owner", "repo", "path/to/file", "msg", "content", "branch"
+    )
     assert "Error updating file: API Error" in res