* fixed tests

* added vector expressions

* added new math expressions

* added string manipulation expressions

* added not_nan, not_null, and is_absent

* added new Array type

* added map and related expressions

* remove dict and list from constant types

* Fixed lint

* added count_if and count_distinct

* added misc expressions

* added error functions

* fixed lint

* fixed typos

Use new object syntax to reference pipeline array type in example

Kokoro tests for pipelines were previously disabled until the backend
supports the feature. This branch will re-enable those tests, when the
backend is ready

Aslo removing index_mode, since this feature was pushed back to a future
release

Rename Function to FunctionExpression, and add a warning that other
changes in the API surface may come before GA

PR created by the Librarian CLI to initialize a release. Merging this PR
will auto trigger a release.

Librarian Version: v1.0.1
Language Image:
us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/python-librarian-generator@sha256:b8058df4c45e9a6e07f6b4d65b458d0d059241dd34c814f151c8bf6b89211209
<details><summary>google-cloud-firestore: 2.23.0</summary>

##
[2.23.0](v2.22.0...v2.23.0)
(2026-01-14)

### Features

* pipelines preview (#1156)
([9462d10](9462d106))

### Bug Fixes

* stream generator type (#1148)
([165d367](165d367c))

</details>