Add Night Watch Dead Code role
New role for detecting and removing unused files, exports, types, and
devDependencies via knip. Assigned to cixzhang, auto-PR mode.
The detector runs out-of-repo (knip binary, config, and runner live in
the operator's workspace) so nothing is added to the public repo's
toolchain. Config is public-API safe: it reads each package's exports
and bin as entry points and ignores CLI templates and vibe-test
baselines. Scope explicitly excludes runtime dependencies (Dependencies
+ Quartermaster), apps/* deletions, and component conventions
(Component Auditor).
Updates the Roles table, role details, coordination schedule, and Home
page links.