feat(pdfa): add FreeTSA timestamping, per-provider folder overrides, individual upload toggles

- Add RFC 3161 timestamping via FreeTSA (PDFA_TIMESTAMP_ENABLED, PDFA_TIMESTAMP_URL)
- Replace PDFA_UPLOAD_TO_PROVIDERS with individual PDFA_UPLOAD_ORIGINAL and PDFA_UPLOAD_PROCESSED
- Add PDFA_UPLOAD_FOLDER setting for per-provider subfolder configuration
- Add GOOGLE_DRIVE_PDFA_FOLDER_ID for Google Drive-specific folder override
- Add folder_override parameter to all 8 folder-using upload tasks
- Add folder_overrides dict parameter to send_to_all_destinations
- Add _compute_pdfa_folder_overrides() and _timestamp_file() helpers
- Expand tests to 26 (timestamping, folder overrides, individual toggles)
- Update docs/ConfigurationGuide.md and .env.demo

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

app/tasks/upload_to_ftp.py

@@ -15,7 +15,7 @@ logger = logging.getLogger(__name__)
 
 
 @celery.task(base=UploadTaskWithRetry, bind=True)
-def upload_to_ftp(self, file_path: str, file_id: int = None):
+def upload_to_ftp(self, file_path: str, file_id: int = None, folder_override: str = None):
     """
     Uploads a file to an FTP server in the configured folder.
 
@@ -97,10 +97,11 @@ def upload_to_ftp(self, file_path: str, file_id: int = None):
             ftp.login(user=settings.ftp_username, passwd=settings.ftp_password)
 
         # Change to target directory if specified
-        if settings.ftp_folder:
+        ftp_folder_setting = folder_override if folder_override is not None else settings.ftp_folder
+        if ftp_folder_setting:
             try:
                 # Try to navigate to the directory, create if it doesn't exist
-                ftp_folder = settings.ftp_folder
+                ftp_folder = ftp_folder_setting
                 # Remove leading slash if present
                 if ftp_folder.startswith("/"):
                     ftp_folder = ftp_folder[1:]
@@ -138,7 +139,7 @@ def upload_to_ftp(self, file_path: str, file_id: int = None):
             "status": "Completed",
             "file": file_path,
             "ftp_host": settings.ftp_host,
-            "ftp_path": f"{settings.ftp_folder}/{filename}" if settings.ftp_folder else filename,
+            "ftp_path": f"{ftp_folder_setting}/{filename}" if ftp_folder_setting else filename,
             "used_tls": used_tls,
         }