chore: import upstream snapshot with attribution

.gitignore

@@ -0,0 +1,71 @@
+# -*- mode: gitignore; -*-
+__pycache__/
+!.vscode/extensions.json
+!.vscode/perspective.code-snippets
+!.vscode/settings.default.json
+!.vscode/tasks.json
+!website/i18n/en.json
+.cache
+.clangd
+.DS_Store
+.emsdk
+.plan
+.pnpm-store
+.ipynb_checkpoints
+.perspectiverc
+.vscode/*
+*.so
+*~
+/.emacs.desktop
+/.emacs.desktop.lock
+/.idea
+/auto/
+/docs/build
+/elpa/
+/eshell/history
+/eshell/lastdir
+/examples/*/build
+/jsconfig.json
+/packages/*/build
+/packages/sigma
+/server/
+/src/include/boost
+benchmark_venv
+dist/
+docs/.docusaurus
+docs/i18n/en.json
+docs/modules.rst
+docs/perspective.*.rst
+docs/static/arrow/
+docs/static/blocks
+docs/static/features
+docs/static/guide
+examples/blocks/src/nypd/nypdccrb.arrow
+node_modules
+packages/jupyterlab/test/config/jupyter/migrated
+py_modules
+python/cmake
+python/cpp
+rust/perspective-client/docs/expression_gen.md
+rust/perspective-client/src/rust/proto.rs
+rust/perspective-js/src/ts/ts-rs
+rust/perspective-server/build
+rust/perspective-python/LICENSE_THIRDPARTY_cargo.yml
+rust/perspective-python/LICENSE.md
+rust/perspective-server/docs/lib_gen.md
+rust/perspective-viewer/src/ts/ts-rs
+rust/perspective/src/ts/ts-rs
+rust/target*
+Vagrantfile
+vcpkg
+venv/
+rust/perspective-python/perspective_python-*.data
+.pytest-cache/
+docs/static/python
+docs/static/node
+docs/static/browser
+docs/static/viewer
+docs/static/react
+rust/perspective-server/build
+target/
+dist-gh-pages