refactor: remove pgvector runtime

harness/tht/cli/search_cmd.py

@@ -255,11 +255,10 @@ def pack_cmd(
     from sqlalchemy.exc import OperationalError
 
     from tht.cli.vector_cmd import make_embedder, open_searcher, require_vector_cfg
-    from tht.ports.vector import VectorReadUnavailable
+    from tht.ports.vector import VectorReadUnavailable, VectorStoreError
     from tht.search import combined_search, schema_tables
     from tht.solved import SOLVED_KIND
     from tht.vectorstore.embeddings import EmbeddingsError
-    from tht.vectorstore.rest_client import VectorRestError
 
     cfg = _load_config_or_exit(config)
     from tht.search.evidence import validate_corpus_workspace
@@ -273,7 +272,7 @@ def pack_cmd(
     evidence: list[dict] = []
     solved: list[dict] = []
     warnings: list[str] = []
-    degrade = (VectorRestError, VectorReadUnavailable, EmbeddingsError, OperationalError)
+    degrade = (VectorStoreError, VectorReadUnavailable, EmbeddingsError, OperationalError)
 
     vec = None
     searcher = embedder = None