ci(ENG-231): Add Rust linting and test workflows with shared caching

[alnoki]

Changes

1. Add rustfmt and clippy as local pre-commit hooks in cfg/pre-commit/lint.yml, using the system toolchain for fast execution
2. Add Rust toolchain (dtolnay/rust-toolchain) and shared dependency cache (Swatinem/rust-cache) to the lint CI workflow
3. Add test.yml workflow that builds assembly via make asm and runs make test, sharing the Rust dependency cache with lint
4. Add .github/actions/install-sbpf composite action that installs and caches the sbpf CLI, pinned to the feat/include-directive branch for multi-file assembly support
5. Update make clean to also remove docs artifacts (node_modules, .vitepress/cache, .vitepress/dist) and the assembly deploy directory
6. Add make lint target and update make all to run lint and test

[linear]

ENG-231