Clean up build tooling and reuse CI artifacts

[reiase]

Summary

After extracting pVisor and pPilot, build setup still carries guest cross-compilation tooling and CI repeats avoidable tool installation and dependency builds. Remove the obsolete setup and reuse build artifacts while preserving the existing test shards and CI gate.

• Skip Rust in Python-only jobs and nextest in build-only jobs; simplify the single-shard examples job.
• Cache pinned MinIO tools and both wheel-build Rust workspaces; share the Cargo target directory between sequential baseline/candidate benchmarks while saving reports separately.
• Include the Web Cargo lockfile in the embedded-assets fingerprint so dependency changes invalidate stale assets.
• Make just ci use non-mutating lint checks and include Python tests, clean both Rust workspaces, and isolate documentation concurrency by ref.
• Update the English and Chinese engineering documentation.

Validation

• Packaging regression suite: 20 passed.
• Benchmark report suite: 7 passed.
• Ruff lint and formatting checks passed for changed Python files.
• actionlint passed for affected workflows and release workflow; shell steps passed syntax checks.
• Checked setup-action inputs, CI gate dependencies, five retained test matrix entries, local CI recipe routing, and MinIO cache miss/hit command paths.
• Strict documentation build and link checks passed for 112 HTML pages.
• git diff --check passed.

Full GitHub Actions runs and timing measurements remain to be performed on this PR.