feat: new settings, CLI skeleton and interface skeletons

Adds the pydantic-settings Settings with validated GITEA_URL, OAuth scopes
and toolsets, the argparse CLI skeleton, catalog.model, identity and
GiteaAPIError. Test fixtures now isolate env, cwd and state paths in tmp.

tests/test_logging_utils.py

@@ -1,4 +1,4 @@
-"""Tests for structured logging helpers and get_issue instrumentation (#14)."""
+"""Tests for structured logging helpers."""
 
 from __future__ import annotations
 
@@ -7,26 +7,12 @@ import logging
 
 import pytest
 
-from aegis_gitea_mcp.config import reset_settings
 from aegis_gitea_mcp.logging_utils import (
     JsonLogFormatter,
     log_event,
     log_nullable_field,
     sanitize_context,
 )
-from aegis_gitea_mcp.tools.read_tools import get_issue_tool
-
-READ_TOOLS_LOGGER = "aegis_gitea_mcp.tools.read_tools"
-
-
-@pytest.fixture(autouse=True)
-def tool_env(monkeypatch: pytest.MonkeyPatch) -> None:
-    """Provide minimal settings environment for response limit helpers."""
-    reset_settings()
-    monkeypatch.setenv("GITEA_URL", "https://gitea.example.com")
-    monkeypatch.setenv("GITEA_TOKEN", "test-token")
-    monkeypatch.setenv("MCP_API_KEYS", "a" * 64)
-    monkeypatch.setenv("ENVIRONMENT", "test")
 
 
 def test_sanitize_context_masks_sensitive_keys() -> None:
@@ -82,39 +68,3 @@ def test_log_nullable_field_characterizes_value(caplog: pytest.LogCaptureFixture
         "is_none": False,
         "value_type": "list",
     }
-
-
-class _NullIssueGitea:
-    """Minimal stub returning an issue with null collection fields."""
-
-    async def get_issue(self, owner: str, repo: str, index: int) -> dict[str, object]:
-        return {
-            "number": index,
-            "title": "Issue",
-            "body": "Body",
-            "state": "open",
-            "labels": None,
-            "assignees": None,
-            "user": None,
-        }
-
-
-@pytest.mark.asyncio
-async def test_get_issue_tool_emits_debug_events(caplog: pytest.LogCaptureFixture) -> None:
-    """get_issue_tool emits start/shape/field-check debug events and still parses."""
-    with caplog.at_level(logging.DEBUG, logger=READ_TOOLS_LOGGER):
-        result = await get_issue_tool(
-            _NullIssueGitea(), {"owner": "acme", "repo": "app", "issue_number": 7}
-        )
-
-    events = [r.getMessage() for r in caplog.records]
-    assert "get_issue.start" in events
-    assert "get_issue.payload_shape" in events
-
-    field_checks = [r.context for r in caplog.records if r.getMessage() == "get_issue.field_check"]
-    assert {"field": "labels", "is_none": True, "value_type": None} in field_checks
-    assert {"field": "user", "is_none": True, "value_type": None} in field_checks
-
-    # Logging must not change behaviour: null collections still parse to empties.
-    assert result["labels"] == []
-    assert result["assignees"] == []