feat: stdio MCP wrapper + Windows Run-key autostart fallback (v1.0.1)

Two production-readiness fixes so colleagues can install cleanly:

1. Plugin's MCP server now spawns `claude-mailbox mcp-stdio`, a small
   stdio MCP wrapper that proxies tool calls to the daemon's REST API.
   Claude Code does not support env-var substitution in HTTP MCP `url`
   fields (issue #46889), so the wrapper is the only way to make the
   daemon URL configurable per machine via CLAUDE_MAILBOX_URL.

2. Windows `install-autostart` now falls back from `schtasks /Create`
   to an HKCU\Software\Microsoft\Windows\CurrentVersion\Run entry
   when Group Policy blocks the Scheduled Task path. Both modes are
   per-user, no admin, persist across logoffs. The chosen mode is
   recorded in ~/.claude-mailbox/autostart-mode so status/start/stop/
   uninstall-autostart pick the right cleanup path.

Also bumps the npm version to 1.0.1 to align with the published 1.0.0
plus this patch.

node/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@kuns/claude-mailbox",
-  "version": "0.1.0",
+  "version": "1.0.1",
   "description": "Standalone MCP mail server that lets parallel Claude sessions coordinate with each other.",
   "type": "module",
   "bin": {