…orresponding GeoSeries methods (#1963)

* chore: create a specs folder for llm-driven development

* include test instructions

* add steps for adding an operator

* create high-level spec

* reformat detailed list

* add detailed steps

* WIP: implement ops for st_buffer, st_centroid, and st_convexhull

* wip: continue implementation

* add note about doctest

* apply new function

* fix doctest

* be more forceful regarding spec-driven development

* feat: implement GeoSeries scalar operators

* revert scalar_op_compiler.py troubles

* switch back to unary

* avoid option type in st_buffer

* Update specs/2025-08-04-geoseries-scalars.md

* Apply suggestions from code review

* remove keyword-only arguments

* fix warnings and mypy errors

* make buffer doctest more robust

…ation easier (#1822)

* Refactor IsNullOp and NotNullOp logic

This change consolidates the definition and compilation logic for IsNullOp, isnull_op, NotNullOp, and notnull_op into a new, dedicated file: `bigframes/operations/isnull_op.py`.

Key changes include:
- Moved operator definitions from `generic_ops.py` to `isnull_op.py`.
- Moved Ibis scalar compilation logic from `scalar_op_compiler.py` to `isnull_op.py`.
- Moved Polars expression compilation logic from `polars/compiler.py` to `isnull_op.py`.
- Updated main compilers (`ScalarOpCompiler` and `PolarsExpressionCompiler`) to directly import and register the compilation functions from `isnull_op.py`.
- Ensured all internal references and naming conventions (`IsNullOp`, `isnull_op`, `NotNullOp`, `notnull_op`) are consistent with the refactored structure.

NOTE: I was unable to perform test validation (unit and system) due to missing project-specific dependencies, primarily `bigframes_vendored` and `test_utils.prefixer`. The changes are provided based on the completion of the refactoring steps as you requested.

* fix circular imports

* bad merge

* fix local pytest

* dont construct polars compiler if no polars

* limit scope to just splitting large files

* Update bigframes/core/compile/compiled.py

* revert unneeded circular import workaround

* combine null ops into generic_ops files

* revert expression change

* Update bigframes/core/compile/polars/operations/__init__.py

* skip polars test for old polars

* Update bigframes/core/compile/ibis_compiler/operations/__init__.py

* add minversion to skips

* more skips

* fix minimum polars version detection

* update colab constraints

* skip polars on 3.10

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#1956)

* fix: add warnings for duplicated or conflicting type hints in bigframes function

* only warm conflict

* 🦉 Updates from OwlBot post-processor

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…e` (#1972)

Also, removes some unnecessary warnings from SQL Cell code paths.

…on` retries (#1973)

…me.where (#1971)

* feat: Allow callable as a conditional or replacement input in DataFrame.where()

* fix lint

#1977)

* feat: df.join lsuffix and rsuffix support

* raise error when on is duplicated.

* rename

* error update.

* test fix.

* add doc and test fixes

* skip pandas 1.x test

* test fixes

* create join on key helper function

* test fix

* test fix

* update join to avoid inplace changes.

* add assertion for columns not changed

* add assertion for columns not changed

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>