test: Add comprehensive tests for v2 API endpoints

Add complete test coverage for all v2 API endpoints using integer IDs:

Knowledge router tests (14 tests):
- Resolve identifier by permalink
- Get entity by ID
- Create entity with observations/relations
- Update entity by ID (PUT)
- Edit entity (PATCH with append/find_replace)
- Delete entity by ID
- Move entity (ID stability)
- Error handling (404s)
- V2-specific features (api_version field)

Project router tests (14 tests):
- Get project by ID
- Update project (path, active status)
- Set default project by ID
- Delete project by ID
- Delete with delete_notes parameter
- Error handling (404s, validation)
- ID stability after operations

All tests properly use entity_repository to look up entity IDs
after creation, as EntityResponse doesn't expose ID field.
Project tests use project_service.add_project() to ensure
projects exist in both database and configuration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jope-bm

tests/api/v2/conftest.py

@@ -0,0 +1,21 @@
+"""Fixtures for V2 API tests."""
+
+import pytest
+
+from basic_memory.models import Project
+
+
+@pytest.fixture
+def v2_project_url(test_project: Project) -> str:
+    """Create a URL prefix for v2 project-scoped routes using project ID.
+
+    This helps tests generate the correct URL for v2 project-scoped routes
+    which use integer project IDs instead of permalinks.
+    """
+    return f"/v2/{test_project.id}"
+
+
+@pytest.fixture
+def v2_projects_url() -> str:
+    """Base URL for v2 project management endpoints."""
+    return "/v2/projects"