Add bl compute commands for Blox workstations

[stuartwdouglas]

Adds a Rust blox crate with a copied orchestrator protocol and Connect client, and introduces bl compute list, get, skus, create, exec, suspend, resume, and delete. bl blox remains a hidden compatibility alias; help, command descriptions, shell completions, examples, and follow-up guidance use bl compute.

The commands reuse the existing BuilderLab login through Compose-style BBIdentity authentication. Creation defaults to DEFAULT_AMD64 at multiple 1 and exposes no cloning or CPU/memory overrides. exec preserves literal arguments, streams stdout/stderr, and returns the remote exit code, with JSONL output available. Lifecycle requests report server state and do not retry uncertain mutations. Execution is noninteractive and may continue after the CLI disconnects.

Validated with just ci (388 tests, formatting, Clippy, release build, and packaging smoke checks). Live bb-public staging checks covered shared authentication, list/get, SKU discovery, and execution output, exit codes, JSONL, and streaming beyond 30 seconds. Creation and lifecycle mutations are covered by mock-service tests.

The compute rename and hidden alias are validated with just check (405 tests, formatting, and Clippy), including identical help through both names, mock-service execution through both names, and alias omission from root help, command descriptions, and all five supported completion shells.