Add mold to system deps (needed by .cargo/config.toml linker setting)
and explicitly install rustfmt/clippy components since mise-action
doesn't always install Rust components.
Replace snap-installed Chromium/chromedriver with Chrome for Testing
installed via npx @puppeteer/browsers. Binaries live in
$MISE_DATA_DIR/chrome-for-testing/ with version-agnostic path lookup.
Add install-e2e mise task and required apt packages to README and CI.
Replace Nix flake with mise for toolchain management, treefmt for
formatting, prek for pre-commit hooks, and a Dockerfile for container
builds. Update CI workflows to use jdx/mise-action instead of Nix.
Add system dependency instructions to README.md and CLAUDE.md.
Merge separate lint and test jobs into a single check job so clippy's
compilation artifacts are reused by tests. Add actions/cache for the
Cargo target directory and registry to enable incremental builds across
runs. Drop unnecessary fetch-depth: 0 from CI jobs.
