feat(cli): modernize standalone CLI foundation

[Teakowa]

Summary

• Replace hand-written opy-cli argument handling with a repository-local clap command model.
• Generate deterministic Bash, Zsh, Fish, and PowerShell completion from that model.
• Add CLI-local terminal/plain/GitHub Actions presentation with explicit renderer and color policies.
• Keep check, inspect, support, and version semantics and exit codes; add the documented completion and check --format json surfaces.
• Keep frontend diagnostics and future compiler integration behind a CLI-owned diagnostic view; no wright, wright-cli, shared CLI crate, or Workshop ownership changes.

Evidence

• Architect final review: APPROVE.
• Independent QA: VERIFIED for command compatibility, completion determinism, PTY/non-TTY/CI/GitHub Actions/NO_COLOR behavior, JSON purity, source spans, workflow escaping, IO errors, and exit codes.
• cargo fmt --all -- --check
• cargo clippy --locked --workspace --all-targets --all-features -- -D warnings
• cargo test --locked --workspace --all-targets --all-features
• python3 -m unittest discover -s compatibility/tests
• git diff --check

Closes #43.