Add LOCAL_DEVELOPMENT.md with test and lint workflow

LOCAL_DEVELOPMENT.md

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+# Tracing – Local development notes
+
+This document complements `CONTRIBUTING.md` with a short, task-oriented checklist for local development.
+
+## 1. Prerequisites
+
+- A recent stable Rust toolchain installed via `rustup`
+- `cargo fmt` and `cargo clippy` components installed
+- Recommended: `rustup component add rustfmt clippy`
+
+You can verify your toolchain with:
+
+~~~bash
+rustc --version
+cargo --version
+~~~
+
+## 2. Run the full test suite
+
+To run tests for the entire workspace:
+
+~~~bash
+cargo test --all
+~~~
+
+To run tests for a specific crate, for example `tracing-subscriber`:
+
+~~~bash
+cargo test -p tracing-subscriber
+~~~
+
+## 3. Formatting and linting
+
+Before opening a pull request, format the code and run Clippy:
+
+~~~bash
+cargo fmt --all
+cargo clippy --all-targets --all-features -- -D warnings
+~~~
+
+This helps keep the code style consistent and prevents new warnings from being introduced.
+
+## 4. Building documentation
+
+To build and inspect the documentation locally:
+
+~~~bash
+cargo doc --all-features
+# or open docs in a browser
+cargo doc --all-features --open
+~~~
+
+## 5. Suggested workflow before a PR
+
+1. `cargo fmt --all`
+2. `cargo clippy --all-targets --all-features -- -D warnings`
+3. `cargo test --all`
+4. Commit and push your changes
+5. Open a pull request and briefly describe:
+   - What you changed
+   - Why the change is useful
+   - How you tested it locally