Add Trusted Server CLI technical spec

[ChristianPavilonis]

Summary

• add a new technical spec for the Trusted Server CLI (ts)
• define the v1 command surface for config, audit, dev, Fastly auth, and Fastly provisioning
• capture safety guarantees, automation/JSON behavior, and open design questions for future provider support

Changes

File	Change
docs/superpowers/specs/2026-04-23-trusted-server-cli-design.md	Add the Trusted Server CLI technical specification, including goals, command surface, shared conventions, Fastly auth/provisioning behavior, and phased implementation plan

Closes

Closes #

Test plan

• cargo test --workspace
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo fmt --all -- --check
• JS tests: cd crates/js/lib && npx vitest run
• JS format: cd crates/js/lib && npm run format
• Docs format: cd docs && npm run format
• WASM build: cargo build --package trusted-server-adapter-fastly --release --target wasm32-wasip1
• Manual testing via fastly compute serve
• Other: documentation-only change; verified the new spec file and command surface in the written doc

Checklist

• Changes follow CLAUDE.md conventions
• No unwrap() in production code — use expect("should ...")
• Uses tracing macros (not println!)
• New code has tests
• No secrets or credentials committed