docs: drop stale MassImportService/ODS references from import deploy docs

The mass-import card no longer parses an ODS spreadsheet and MassImportService
was deleted (#674); /import now holds the normalizer's canonical artifacts
(canonical-*.xlsx + canonical-persons-tree.json) plus <index>.pdf files, read
by the canonical importer. Fix the IMPORT_HOST_DIR descriptions in
DEPLOYMENT.md and docker-compose.prod.yml accordingly.

Refs #686

docker-compose.prod.yml

@@ -26,8 +26,10 @@
 #   MAIL_HOST, MAIL_PORT,       SMTP relay (production only; staging uses mailpit)
 #   MAIL_USERNAME, MAIL_PASSWORD
 #   APP_MAIL_FROM               sender address (e.g. noreply@raddatz.cloud)
-#   IMPORT_HOST_DIR             absolute host path holding ONLY the ODS
-#                               spreadsheet and PDFs for /admin/system mass
+#   IMPORT_HOST_DIR             absolute host path holding the canonical
+#                               import artifacts (canonical-*.xlsx +
+#                               canonical-persons-tree.json) and the
+#                               <index>.pdf files for /admin/system
 #                               import — mounted read-only at /import inside
 #                               the backend. Compose refuses to start when
 #                               this var is unset, so staging and prod cannot
@@ -217,12 +219,13 @@ services:
     # Bound to localhost only — Caddy fronts external traffic.
     ports:
       - "127.0.0.1:${PORT_BACKEND}:8080"
-    # Host path holding the ODS spreadsheet + PDFs for the mass-import endpoint.
-    # Read-only; MassImportService only reads (Files.list / Files.walk on /import).
+    # Host path holding the canonical import artifacts (canonical-*.xlsx +
+    # canonical-persons-tree.json) + <index>.pdf files for the import endpoint.
+    # Read-only; the canonical importer only reads them from /import.
     # Required — no default — so staging and prod cannot accidentally share an
     # import source. CI workflows pin this per-env (see .gitea/workflows/).
     volumes:
-      - ${IMPORT_HOST_DIR:?Set IMPORT_HOST_DIR to a host path holding the mass-import payload (ODS + PDFs). See docs/DEPLOYMENT.md.}:/import:ro
+      - ${IMPORT_HOST_DIR:?Set IMPORT_HOST_DIR to a host path holding the import payload (canonical artifacts + <index>.pdf files). See docs/DEPLOYMENT.md.}:/import:ro
     environment:
       SPRING_DATASOURCE_URL: jdbc:postgresql://db:5432/archiv
       SPRING_DATASOURCE_USERNAME: archiv