docs: align documentation with current CLI

[cursor]

Summary

• Updated CLI and README command references for current commands, flags, sidecar setup behavior, hook controls, and skill installation targets.
• Refreshed architecture docs for current package layout, config keys, env vars, error handling, and validate behavior.
• Corrected getting started, hooks, skills, and AGENTS guidance to match current code and Taskfile conventions.

Verification

• git diff --check