Pathway

Added
- `pw.io.kafka.read` now supports reading entries starting from a specified timestamp.
- `pw.io.nats.read` and `pw.io.nats.write` methods for reading from and writing Pathway tables to NATS.

Changed
- `pw.Table.diff` now supports setting `instance` parameter that allows computing differences for multiple groups.
- `pw.io.postgres.write_snapshot` now keeps the Postgres table fully in sync with the current state of the table in Pathway. This means that if an entry is deleted in Pathway, the same entry will also be deleted from the Postgres table managed by the output connector.

Fixed
- `pw.PyObjectWrapper` is now picklable.
- `query_as_of_now` of `pw.stdlib.indexing.DataIndex` and `pw.stdlib.indexing.HybridIndex` now work in constant memory for infinite query stream (no query-related data is kept after query is answered).

Added
- `pw.io.mongodb.write` connector for writing Pathway tables in MongoDB.
- `pw.io.s3.read` now supports downloading objects from an S3 bucket in parallel.

Changed
- `pw.io.fs.read` performance has been improved for directories containing a large number of files.

Added
- `pw.io.deltalake.read` now supports custom S3 Delta Lakes with HTTP endpoints.
- `pw.io.deltalake.read` now supports specifying both a custom endpoint and a custom region for Delta Lakes via `pw.io.s3.AwsS3Settings`.

Changed
- Indices in `pathway.stdlib.indexing.nearest_neighbors` can now work also on numpy arrays. Previously they only accepted `list[float]`. Working with numpy arrays improves memory efficiency.
- `pw.io.s3.read` has been optimized to minimize new object requests whenever possible.
- It is now possible to set the size limit of cache in `pw.udfs.DiskCache`.
- State persistence now uses a single backend for both metadata and stream storage. The `pw.persistence.Config.simple_config` method is therefore deprecated. Now you can use the `pw.persistence.Config` constructor with the same parameters that were previously used in `simple_config`.

Fixed
- `pw.io.bigquery.write` connector now correctly handles `pw.Json` columns.

Fixed
- `pw.temporal.session` and `pw.temporal.asof_join` now correctly works with multiple entries with the same time.
- Fixed an issue in `pw.stdlib.indexing` where filters would cause runtime errors while using `HybridIndexFactory`.

Added
- **Experimental** A ``pw.xpacks.llm.document_store.DocumentStore`` to process and index documents.
- ``pw.xpacks.llm.servers.DocumentStoreServer`` used to expose REST server for retrieving documents from ``pw.xpacks.llm.document_store.DocumentStore``.
- `pw.xpacks.stdlib.indexing.HybridIndex` used for querying multiple indices and combining their results.
- `pw.io.airbyte.read` now also supports streams that only operate in `full_refresh` mode.

Changed
- Running servers for answering queries is extracted from `pw.xpacks.llm.question_answering.BaseRAGQuestionAnswerer` into `pw.xpacks.llm.servers.QARestServer` and `pw.xpacks.llm.servers.QASummaryRestServer`.
- **BREAKING**: `query` and `query_as_of_now` of `pathway.stdlib.indexing.data_index.DataIndex` now produce an empty list instead of `None` if no match is found.

Fixed
- `pw.io.deltalake.read` and `pw.io.deltalake.write` now correctly work with lakes hosted in S3 over min.io, Wasabi and Digital Ocean.

Added
- The Pathway CLI command `spawn` can now execute code directly from a specified GitHub repository.
- A new CLI command, `spawn-from-env`, has been added. This command runs the Pathway CLI `spawn` command using arguments provided in the `PATHWAY_SPAWN_ARGS` environment variable.