Familiars library: tick-to-bind catalog for harnesses, clients, and plugins

Coven would benefit from a familiars library — a curated, browsable catalog of the components in the OpenCoven ecosystem (harnesses like Codex and Claude Code, plus clients and plugins such as comux, OpenMeow, and the @opencoven/coven plugin), each with a short description and a single tick to enable. Standing up a working setup today means installing each harness, running its own auth, checking coven doctor, and wiring clients to the daemon by hand across several docs, with no one place to see what's available or switch it on. A catalog would collapse that into picking the boxes you want and cut time-to-first-session for new users and standard familiars.

The idea is that ticking a familiar would bind it and let coven and an existing agent that has been onboarded find each other automatically, rather than being hand-configured. Because everything already rendezvouses at a prearranged daemon socket, "they find each other" just means they register at the existing authority boundary — no peer-to-peer discovery or new network surface required. Binding would stay a UX convenience rather than a grant of trust: enabling a harness resolves to the allowlist the Rust daemon already enforces, provider credentials stay in each harness's own login flow, and the daemon keeps revalidating every request. The result is less setup friction without moving any enforcement out of Rust.