Adds Pinecone as a supported vector database option.
- Implements `PineconeClient` with support for common operations: `add`, `query`, `delete`, `reset`.
- Emulates namespace support using metadata filtering (`collection_name` prefix).
- Dynamically configures Pinecone via the following env vars:
- `PINECONE_API_KEY`
- `PINECONE_ENVIRONMENT`
- `PINECONE_INDEX_NAME`
- `PINECONE_DIMENSION`
- `PINECONE_METRIC`
- `PINECONE_CLOUD`
- Integrates cleanly with the vector DB abstraction layer.
- Includes markdown documentation under `docs/getting-started/env-configuration.md`.
BREAKING CHANGE: None