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/userinfo_routes.py

@@ -13,11 +13,13 @@ import traceback
 from pathlib import Path
 from typing import Any
 
+from httpx import BasicAuth
 from jinja2 import Environment, FileSystemLoader
 from starlette.authentication import requires
 from starlette.requests import Request
 from starlette.responses import HTMLResponse, JSONResponse
 
+from nextcloud_mcp_server.auth.permissions import is_nextcloud_admin
 from nextcloud_mcp_server.client import NextcloudClient
 from nextcloud_mcp_server.config import get_settings
 
@@ -56,8 +58,6 @@ async def _get_authenticated_client_for_userinfo(request: Request) -> NextcloudC
         if not all([nextcloud_host, username, password]):
             raise RuntimeError("BasicAuth credentials not configured")
 
-        from httpx import BasicAuth
-
         assert nextcloud_host is not None
         assert username is not None
         assert password is not None
@@ -129,7 +129,9 @@ async def _get_processing_status(request: Request) -> dict[str, Any] | None:
         # Get Qdrant client and query indexed count
         indexed_count = 0
         try:
-            from nextcloud_mcp_server.vector.qdrant_client import get_qdrant_client
+            from nextcloud_mcp_server.vector.qdrant_client import (  # noqa: PLC0415
+                get_qdrant_client,
+            )
 
             qdrant_client = await get_qdrant_client()
 
@@ -431,8 +433,6 @@ async def user_info_html(request: Request) -> HTMLResponse:
     # Check if user is admin (for Webhooks tab)
     is_admin = False
     try:
-        from nextcloud_mcp_server.auth.permissions import is_nextcloud_admin
-
         # Get authenticated Nextcloud client
         nc_client = await _get_authenticated_client_for_userinfo(request)
         is_admin = await is_nextcloud_admin(request, nc_client._client)
@@ -471,8 +471,6 @@ async def user_info_html(request: Request) -> HTMLResponse:
     # Get Nextcloud host for generating links to apps (used by viz tab)
     # Use public issuer URL if available (for browser-accessible links),
     # otherwise fall back to NEXTCLOUD_HOST from settings
-    from nextcloud_mcp_server.config import get_settings
-
     settings = get_settings()
     nextcloud_host_for_links = (
         os.getenv("NEXTCLOUD_PUBLIC_ISSUER_URL") or settings.nextcloud_host