Reorganize host runtime files

Move the host-only proxy entrypoints into a dedicated directory so it is obvious which files run on the host.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

host/stop.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+set -eu
+
+script_dir=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
+pid_file="$script_dir/state/server.pid"
+
+if [ ! -f "$pid_file" ]; then
+  printf 'Proxy is not running\n'
+  exit 0
+fi
+
+pid=$(cat "$pid_file" 2>/dev/null || true)
+
+if [ -z "${pid:-}" ]; then
+  rm -f "$pid_file"
+  printf 'Stale pid file removed\n'
+  exit 0
+fi
+
+if kill -0 "$pid" 2>/dev/null; then
+  kill "$pid"
+  printf 'Stopped proxy pid=%s\n' "$pid"
+else
+  printf 'Proxy process was not running, removing stale pid file\n'
+fi
+
+rm -f "$pid_file"