build(huggingface): add langflow-base[local] to the complete extra

llama-cpp-python lives in the [local] extra of langflow-base but wasn't
included in [complete], so the langflow main install (which pulls
langflow-base[complete]) shipped without it. The new HuggingFace local
provider needs llama-cpp-python at runtime, so the user saw:

  ImportError: Could not import llama-cpp-python library.

Pulling [local] into [complete] makes the full langflow install include
it without bloating bare langflow-base setups (which can still skip it).

For an existing dev env, install on demand:
  uv pip install llama-cpp-python
or:
  uv sync --reinstall

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/backend/base/pyproject.toml

@@ -366,6 +366,7 @@ ibm-watsonx-clients = [
 ]
 
 complete = [
+    "langflow-base[local]",
     "langflow-base[couchbase]",
     "langflow-base[cassandra]",
     "langflow-base[clickhouse]",