jax

Merge pull request #1 from tarnishablec/v0.3

chore(cargo): add `coverage` alias to `.cargo/config.toml` for streamlined test coverage commands

refactor(runtime): replace type-based shard lookup with static-ID mechanism

refactor(report): replace `Box<dyn Error>` with `JaxError` in `ShardError` for clearer error handling and update dependencies to version 0.3.0

chore: bump workspace version to 0.3.0