DIAGNOSTIC ONLY: remove hooks.json to confirm Cowork sync theory

[isabelle-cedar]

⚠️ Diagnostic only — merge briefly, test, then revert immediately

Not a real fix. This removes cedar-plugin/hooks/hooks.json entirely to test
whether that's what's causing Cowork's marketplace sync to fail.

Why

The real underlying error (from claude.ai-web.log, not the generic UI
message) is:

Invalid hooks config at 'hooks.UserPromptSubmit.0.hooks.0.type': Input should be 'command', 'prompt' or 'agent'
Invalid hooks config at 'hooks.Stop.0.hooks.0.type': Input should be 'command', 'prompt' or 'agent'
Invalid hooks config at 'hooks.PostToolUse.0.hooks.0.type': Input should be 'command', 'prompt' or 'agent'

This exactly matches anthropics/claude-code#35653
(closed NOT_PLANNED) — Cowork's server-side marketplace-sync content validator
only accepts command/prompt/agent as hook types, and rejects mcp_tool
(what all three of Cedar's hooks use) outright.

Cowork's "Add from a repository" field doesn't support branch-pinning
(@ref/#ref both fail — confirmed live), so the only way to test this
theory against the real sync path is a real (if brief) change on main.

Plan

1. Merge this PR.
2. Immediately retest "Add marketplace" in Cowork.
3. Revert right after, regardless of outcome — this is not staying merged.

🤖 Generated with Claude Code