docs: record issue #24's smoke-test findings and local litellm-pgvector patches

memory-knowledgebase.md no longer says 'not yet verified' — it's been
smoke-tested end-to-end (direct search + the file_search tool on a chat
completion) and the bugs found are fixed in the preceding commits.
VENDORED.md documents the three local patches on top of the upstream
litellm-pgvector commit so a future re-vendor doesn't silently drop them.

vendor/litellm-pgvector/VENDORED.md

@@ -1,8 +1,25 @@
 Vendored from https://github.com/BerriAI/litellm-pgvector at commit
-`b553f84a32f580b4303297df5567f25912b59d93` (main, 2026-09-02) — no changes
-made to the source. See `docker-compose.yml`'s `litellm-pgvector` service
-comment for why this is vendored instead of built from a remote git context.
+`b553f84a32f580b4303297df5567f25912b59d93` (main, 2026-09-02). See
+`docker-compose.yml`'s `litellm-pgvector` service comment for why this is
+vendored instead of built from a remote git context.
+
+**Local changes on top of that commit** (found smoke-testing issue #24 —
+without these, the store can never be searched or written to):
+
+- `prisma/schema.prisma`: `Embedding.embedding` was `vector(1536)`
+  (OpenAI ada-002's size); changed to `vector(768)` to match this stack's
+  actual embedding model (nomic-embed-text-v1.5).
+- `models.py` / `main.py`: `POST /v1/vector_stores` always minted a random
+  UUID for the new store's `id`, ignoring anything the caller asked for.
+  Added an optional `id` field to `VectorStoreCreateRequest` and made
+  `create_vector_store` use it when given — `litellm-config.yaml`'s
+  `vector_store_registry` addresses this store by a fixed id
+  (`memory-and-notes`), which never matched a real row otherwise.
+
+Re-applying these after a re-vendor: diff this directory against upstream
+before overwriting, or just redo the three edits above.
 
 To update: `git clone https://github.com/BerriAI/litellm-pgvector.git`
-somewhere, copy everything except `.git/` over this directory, update the
-commit hash above, and run `./scripts/update.sh`.
+somewhere, copy everything except `.git/` over this directory, re-apply the
+local changes above, update the commit hash above, and run
+`./scripts/update.sh`.