Cleanup: Delete ALL 242 shims, update ALL consumer imports

klausur-service: 183 shims deleted, 26 test files + 8 source files updated
backend-lehrer: 59 shims deleted, main.py + 8 source files updated

All imports now use the new package paths directly.
Zero shims remaining in the entire codebase.

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

klausur-service/backend/tests/test_byoeh.py

@@ -514,7 +514,7 @@ class TestEncryptionUtils:
 
     def test_hash_key(self):
         """Key hashing produces consistent results."""
-        from eh_pipeline import hash_key
+        from korrektur.eh_pipeline import hash_key
         import os
 
         passphrase = "test-secret-passphrase"
@@ -527,7 +527,7 @@ class TestEncryptionUtils:
 
     def test_verify_key_hash(self):
         """Key hash verification works correctly."""
-        from eh_pipeline import hash_key, verify_key_hash
+        from korrektur.eh_pipeline import hash_key, verify_key_hash
         import os
 
         passphrase = "test-secret-passphrase"
@@ -539,7 +539,7 @@ class TestEncryptionUtils:
 
     def test_chunk_text(self):
         """Text chunking produces correct overlap."""
-        from eh_pipeline import chunk_text
+        from korrektur.eh_pipeline import chunk_text
 
         text = "A" * 2000  # 2000 characters
         chunks = chunk_text(text, chunk_size=1000, overlap=200)
@@ -550,7 +550,7 @@ class TestEncryptionUtils:
 
     def test_encrypt_decrypt_text(self):
         """Text encryption and decryption round-trip."""
-        from eh_pipeline import encrypt_text, decrypt_text
+        from korrektur.eh_pipeline import encrypt_text, decrypt_text
 
         plaintext = "Dies ist ein geheimer Text."
         passphrase = "geheim123"