feat: Remove URL rewriting in favor of proper nextcloud config

Remove URL rewriting logic from MCP server that was converting
      public URLs to internal Docker URLs. This was a workaround for
      Nextcloud's overwritehost setting forcing URLs to localhost:8080.

      Changes:
      - Remove OIDC endpoint rewriting in app.py (setup_oauth_config)
      - Remove OIDC_JWKS_URI override support (no longer needed)
      - Remove URL rewriting in browser_oauth_routes.py
      - Remove URL rewriting in token_broker.py
      - Update Helm chart values and README
      - Add hybrid auth setup unit tests
      - Update Astrolabe admin UI for Vue 3

      The proper fix is in the previous commit which removes the
      overwritehost setting from Nextcloud, allowing it to respect
      the Host header from incoming requests.

nextcloud_mcp_server/migrations.py

@@ -8,9 +8,8 @@ provides CLI integration.
 import logging
 from pathlib import Path
 
-from alembic.config import Config
-
 from alembic import command
+from alembic.config import Config
 
 logger = logging.getLogger(__name__)