Feature Request: Server/IPC hook type for persistent hook processes

Problem

Hooks currently use type: "command" which spawns a new Node.js process per hook invocation. For plugins with many hooks (e.g., 63 entries), this means 7+ process spawns per tool call, each incurring ~50-80ms of V8 cold-start overhead. On a typical Bash call:

• PermissionRequest: 2 spawns × ~75ms = ~150ms
• PreToolUse: 3-5 spawns × ~75ms = ~225-375ms
• PostToolUse: 3 spawns × ~75ms = ~225ms (partially async)
• Total blocking overhead: ~375-525ms per tool call

The async: true flag (CC 2.1.45) helps for non-blocking hooks, but blocking hooks (permission, pre-tool validation) cannot be made async.

Proposed Solution

Add a type: "server" hook type that connects to a persistent process via Unix domain socket (or named pipe on Windows):

{
  "hooks": {
    "PreToolUse": [{
      "type": "server",
      "socket": "/tmp/my-plugin-{sessionId}.sock",
      "matcher": "Bash"
    }],
    "PermissionRequest": [{
      "type": "server", 
      "socket": "/tmp/my-plugin-{sessionId}.sock",
      "matcher": "Bash"
    }]
  }
}

How it works

1. Plugin starts a daemon at SessionStart (via existing type: "command" hook)
2. Daemon listens on Unix socket, keeps all hook logic warm in memory
3. CC sends hook events as JSON over IPC instead of spawning processes
4. Daemon returns hook result over IPC
5. Daemon shuts down at Stop event

Expected performance

• Per-call overhead: ~2-5ms (IPC round-trip) vs ~75ms (process spawn)
• 94-99% reduction in hook latency
• Zero V8 cold-starts after initial daemon startup
• Single process instead of 7+ per tool call

Workaround

We're currently using a "hook proxy" pattern where spawned processes connect to a self-managed daemon via Unix socket. This works but adds ~15ms overhead per call (Node start + socket connect). Native CC support would eliminate this entirely.

Context

OrchestKit plugin (62 skills, 37 agents, 63 global hooks). The hook system is the primary performance bottleneck — LLM calls take seconds but hook overhead adds 500ms+ of unnecessary latency to every tool call.