Vector embedder and large blocks

[gabrc52]

https://github.com/ergut/mcp-logseq/blob/main/VECTOR_SEARCH.md

Some blocks give a 400 error from Ollama

Logseq itself is aware of large blocks and does not index them

Large block will not be editable or searchable to not slow down the app, please use another editor to edit this block.

However, this embedder does not seem to exclude them. These can be large blocks of code that shouldn't get embeddings anyway.