refactor: enforce PLC0415 (import-outside-top-level) for source code

Enable ruff PLC0415 rule for all source files (tests excluded via
per-file-ignores). Move 136 inline imports to top-level across 33 files.
8 imports suppressed with noqa for legitimate reasons: circular
dependencies (client/__init__.py, context.py), optional dependency
guards (app.py document processors, auth/userinfo_routes.py), and
post-env-setup imports (smithery_main.py).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nextcloud_mcp_server/auth/scope_authorization.py

@@ -9,6 +9,8 @@ from mcp.server.auth.provider import AccessToken
 from mcp.server.fastmcp import Context
 from mcp.server.fastmcp.utilities.context_injection import find_context_parameter
 
+from nextcloud_mcp_server.config import get_settings
+
 logger = logging.getLogger(__name__)
 
 
@@ -132,8 +134,6 @@ def require_scopes(*required_scopes: str):
             # Check if offline access is enabled
             # Use settings.enable_offline_access which handles both ENABLE_BACKGROUND_OPERATIONS (new)
             # and ENABLE_OFFLINE_ACCESS (deprecated) environment variables
-            from nextcloud_mcp_server.config import get_settings
-
             settings = get_settings()
             enable_offline_access = settings.enable_offline_access