safe-bash: add bzip2/xz/zstd (de)compression

[kamilio]

Missing: bzip2/bunzip2/bzcat, xz/unxz/xzcat, zstd/unzstd/zstdcat. Only gzip/gunzip/zcat exist. (The xz/zstd/bzip2 strings in search/file-types.ts are extension detection for rg -t, not real codecs.)

Behavior: mirror the existing bounded gzip commands (streaming, -d, -c, -k, per-chunk + aggregate output-budget caps so decompression bombs are bounded). zstd is increasingly the default in modern toolchains. Prefer a portable codec so this also works on the Workers/no-nodejs_compat bundle (see #672).

From the safe-bash command gap analysis (2026-09-08). Sandbox constraints apply: bounded input/CPU/memory, VFS-only paths, cooperative cancellation, no host process/network beyond the existing curl authorizer.

[kamilio]

Released in poe-code 15.0.12, from main commit 52a76cc880cbcc6088ccd5dc65b70e0a86c24b90. Release validation and publication succeeded, including all four complete Bash shards.

All nine bzip2/xz/zstd commands are available through the public agent commands, with streaming compression/decompression, VFS file handling, native-format interoperability, bounded input/output/memory, and cooperative cancellation.

Installed-package verification passed 442 checks each on Node, Bun, the browser bundle, and workerd without nodejs_compat, including 54 compression checks. All three public type profiles and bundle graph checks passed. The published tarball integrity and signed SLSA provenance match the repository, commit, and release workflow run. A freshly rendered and inspected CLI screenshot confirmed all three VFS file round trips.

Local validation also passed the normal build, full lint, maintained non-Bash route, affected root checks, and complete Bash route. Earlier intermittent local cleanup-test timeouts were investigated without changing assertions or deadlines; the unchanged focused check, final full Bash route, and all release Bash shards passed.