refactor(api): split management.py into domain-focused modules

Split the monolithic management.py (1988 lines) into 4 focused modules:
- management.py: Server status, user sessions, shared helpers (~520 lines)
- passwords.py: App password provisioning for BasicAuth mode (~300 lines)
- webhooks.py: Webhook registration management (~290 lines)
- visualization.py: Search and PDF preview endpoints (~810 lines)

Backward compatibility maintained via __init__.py re-exports.
Updated test imports to use new module paths.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

nextcloud_mcp_server/api/__init__.py

@@ -3,4 +3,74 @@
 Provides REST endpoints for the Nextcloud PHP app to query server status,
 user sessions, and vector sync metrics. All endpoints use OAuth bearer token
 authentication via the UnifiedTokenVerifier.
+
+This package is organized into modules by domain:
+- management.py: Server status, user sessions, shared helpers
+- passwords.py: App password provisioning for multi-user BasicAuth
+- webhooks.py: Webhook registration management
+- visualization.py: Search and PDF visualization endpoints
 """
+
+# Re-export all public functions for backward compatibility
+from nextcloud_mcp_server.api.management import (
+    __version__,
+    _parse_float_param,
+    _parse_int_param,
+    _sanitize_error_for_client,
+    _validate_query_string,
+    extract_bearer_token,
+    get_server_status,
+    get_user_session,
+    get_vector_sync_status,
+    revoke_user_access,
+    validate_token_and_get_user,
+)
+from nextcloud_mcp_server.api.passwords import (
+    delete_app_password,
+    get_app_password_status,
+    provision_app_password,
+)
+from nextcloud_mcp_server.api.visualization import (
+    get_chunk_context,
+    get_pdf_preview,
+    unified_search,
+    vector_search,
+)
+from nextcloud_mcp_server.api.webhooks import (
+    create_webhook,
+    delete_webhook,
+    get_installed_apps,
+    list_webhooks,
+)
+
+__all__ = [
+    # Version
+    "__version__",
+    # Shared helpers (from management.py)
+    "extract_bearer_token",
+    "validate_token_and_get_user",
+    "_sanitize_error_for_client",
+    "_parse_int_param",
+    "_parse_float_param",
+    "_validate_query_string",
+    # Status endpoints (from management.py)
+    "get_server_status",
+    "get_vector_sync_status",
+    # Session endpoints (from management.py)
+    "get_user_session",
+    "revoke_user_access",
+    # Password endpoints (from passwords.py)
+    "provision_app_password",
+    "get_app_password_status",
+    "delete_app_password",
+    # Webhook endpoints (from webhooks.py)
+    "get_installed_apps",
+    "list_webhooks",
+    "create_webhook",
+    "delete_webhook",
+    # Visualization endpoints (from visualization.py)
+    "unified_search",
+    "vector_search",
+    "get_chunk_context",
+    "get_pdf_preview",
+]