fix: merge main into feature branch - resolve all merge conflicts cleanly

Merges origin/main (v0.156.0) into the classification feature branch,
properly resolving all 23 merge conflicts:

- Auto-generated files (BUILD_DATE, VERSION, etc.): accept main's version
- Non-classification files (SharePoint, QR auth, session mgmt, mobile): accept main's version
- Classification files (api/__init__.py, models.py, migrations/env.py, conftest.py):
  keep classification additions alongside main's content

Previously the branch was incorrectly removing files from main (SharePoint
integration, QR scanner, session management). This merge properly preserves
all main branch content while maintaining the classification feature additions.

Migration chain validated: 038_add_classification_rules chains from
037_add_user_sessions_and_qr_challenges.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

docs/UserGuide.md

@@ -170,7 +170,7 @@ The **Integrations** page (`/integrations`) provides a unified view of all your
    - **S3** — bucket, region, access key, secret key
    - **WebDAV / Nextcloud** — URL, folder, username, password
    - **FTP / SFTP** — host, port, remote path, username, password
-   - **Dropbox / Google Drive / OneDrive** — folder path, with a link to the OAuth setup page
+   - **Dropbox / Google Drive / OneDrive / SharePoint** — folder path, with a link to the OAuth setup page
    - **Email Forward** — recipient email address
    - **Watch Folder** — source type (Local, S3, Dropbox, Google Drive, OneDrive, Nextcloud, WebDAV), per-type config fields, delete after processing toggle
    - **Paperless NGX** — URL and API token