feat: migrate ORM base to sqlmodel-ext, add file viewers and WOPI integration

- Migrate SQLModel base classes, mixins, and database management to
  external sqlmodel-ext package; remove sqlmodels/base/, sqlmodels/mixin/,
  and sqlmodels/database.py
- Add file viewer/editor system with WOPI protocol support for
  collaborative editing (OnlyOffice, Collabora)
- Add enterprise edition license verification module (ee/)
- Add Dockerfile multi-stage build with Cython compilation support
- Add new dependencies: sqlmodel-ext, cryptography, whatthepatch

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

routers/api/v1/admin/__init__.py

@@ -9,7 +9,7 @@ from sqlmodels import (
     User, ResponseBase,
     Setting, Object, ObjectType, Share, AdminSummaryResponse, MetricsSummary, LicenseInfo, VersionInfo,
 )
-from sqlmodels.base import SQLModelBase
+from sqlmodel_ext import SQLModelBase
 from sqlmodels.setting import (
     SettingItem, SettingsListResponse, SettingsUpdateRequest, SettingsUpdateResponse,
 )
@@ -17,6 +17,7 @@ from sqlmodels.setting import SettingsType
 from utils import http_exceptions
 from utils.conf import appmeta
 from .file import admin_file_router
+from .file_app import admin_file_app_router
 from .group import admin_group_router
 from .policy import admin_policy_router
 from .share import admin_share_router
@@ -44,6 +45,7 @@ admin_router = APIRouter(
 admin_router.include_router(admin_group_router)
 admin_router.include_router(admin_user_router)
 admin_router.include_router(admin_file_router)
+admin_router.include_router(admin_file_app_router)
 admin_router.include_router(admin_policy_router)
 admin_router.include_router(admin_share_router)
 admin_router.include_router(admin_task_router)