chore: add claude md files (#2531)

Gives basic context to Claude about how to do common tasks in the repo.

CLAUDE.md

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+LanceDB is a database designed for retrieval, including vector, full-text, and hybrid search.
+It is a wrapper around Lance. There are two backends: local (in-process like SQLite) and
+remote (against LanceDB Cloud).
+
+The core of LanceDB is written in Rust. There are bindings in Python, Typescript, and Java.
+
+Project layout:
+
+* `rust/lancedb`: The LanceDB core Rust implementation.
+* `python`: The Python bindings, using PyO3.
+* `nodejs`: The Typescript bindings, using napi-rs
+* `java`: The Java bindings
+
+(`rust/ffi` and `node/` are for a deprecated package. You can ignore them.)
+
+Common commands:
+
+* Check for compiler errors: `cargo check --features remote --tests --examples`
+* Run tests: `cargo test --features remote --tests`
+* Run specific test: `cargo test --features remote -p <package_name> --test <test_name>`
+* Lint: `cargo clippy --features remote --tests --examples`
+* Format: `cargo fmt --all`
+
+Before committing changes, run formatting.

nodejs/CLAUDE.md

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+These are the typescript bindings of LanceDB.
+The core Rust library is in the `../rust/lancedb` directory, the rust binding
+code is in the `src/` directory and the typescript bindings are in
+the `lancedb/` directory.
+
+Whenever you change the Rust code, you will need to recompile: `npm run build`.
+
+Common commands:
+* Build: `npm run build`
+* Lint: `npm run lint`
+* Fix lints: `npm run lint-fix`
+* Test: `npm test`
+* Run single test file: `npm test __test__/arrow.test.ts`

python/CLAUDE.md

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+These are the Python bindings of LanceDB.
+The core Rust library is in the `../rust/lancedb` directory, the rust binding
+code is in the `src/` directory and the Python bindings are in the `lancedb/` directory.
+
+Common commands:
+
+* Build: `make develop`
+* Format: `make format`
+* Lint: `make check`
+* Fix lints: `make fix`
+* Test: `make test`
+* Doc test: `make doctest`
+
+Before committing changes, run lints and then formatting.
+
+When you change the Rust code, you will need to recompile the Python bindings: `make develop`.