Fix: Update all old-style imports inside packages to new paths

65 files in klausur-service packages + 3 in backend-lehrer packages
had stale imports referencing deleted shim modules.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

klausur-service/backend/worksheet/__init__.py

@@ -2,5 +2,5 @@
 worksheet package — worksheet editor, NRU generator, cleanup.
 
 Backward-compatible re-exports: consumers can still use
-``from worksheet_editor_api import ...`` etc. via the shim files in backend/.
+``from worksheet.editor_api import ...`` etc. via the shim files in backend/.
 """

klausur-service/backend/worksheet/editor_api.py

@@ -366,7 +366,7 @@ async def reconstruct_document_from_session(request: ReconstructRequest):
 async def get_available_sessions():
     """Get list of available vocab sessions that can be reconstructed."""
     try:
-        from vocab_worksheet_api import _sessions
+        from vocab.worksheet.api import _sessions
 
         available = []
         for session_id, session in _sessions.items():

klausur-service/backend/worksheet/editor_reconstruct.py

@@ -31,7 +31,7 @@ async def reconstruct_document_logic(request: ReconstructRequest) -> Reconstruct
     Returns ReconstructResponse ready to send to the client.
     """
     from fastapi import HTTPException
-    from vocab_worksheet_api import _sessions, convert_pdf_page_to_image
+    from vocab.worksheet.api import _sessions, convert_pdf_page_to_image
 
     # Check if session exists
     if request.session_id not in _sessions: