feat: preserve Wiki vectors across knowledge transfers and add local BGE-M3

Unify Wiki reading, preserve metadata and graph links, add asynchronous file-backed transfers, and reuse compatible vectors. Includes regression coverage and live acceptance notes.

.gitignore

@@ -91,6 +91,7 @@ offline-backend-20260512/backend/tests/*
 # Keep the openGauss URL/dialect/schema compatibility regression coverage versioned.
 !offline-backend-20260512/backend/tests/test_gauss_database.py
 !offline-backend-20260512/backend/tests/test_llmwiki_weknora.py
+!offline-backend-20260512/backend/tests/test_llmwiki_knowledge_management.py
 !offline-backend-20260512/backend/tests/test_health_auth_bypass.py
 # Keep formal Word OOXML and embedded-font regression coverage versioned.
 !offline-backend-20260512/backend/tests/test_word_export.py
@@ -172,8 +173,10 @@ docs/backups
 # Frontend skills components must be tracked (excluded from the broad skills/ ignore above)
 !frontend-web/src/components/workspace/skills/
 
-# uv lockfile (not tracked per project preference)
-offline-backend-20260512/backend/uv.lock
+# uv lockfile (not tracked per project preference)
+offline-backend-20260512/backend/uv.lock
+
+!offline-backend-20260512/backend/tests/test_wiki_package_roundtrip.py
 
 # Local-only scratch directory (not committed)
 0622/