feat(node): add TypeScript sibling project for npm-based install

Introduces @kuns/claude-mailbox under node/, a wire-compatible TypeScript
port of the .NET daemon that distributes via the public Gitea npm registry.
The .NET project stays in src/ClaudeMailbox/ untouched; users pick whichever
flavor they prefer.

- node/ project: fastify + @modelcontextprotocol/sdk StreamableHTTPServerTransport
  + better-sqlite3, schema and wire surface match the C# version (port 47822,
  X-Mailbox header, MCP tool names, snake_case SQLite columns)
- Cross-platform autostart: Scheduled Task (Win, no admin) / Windows Service
  (Win, --service) / launchd (mac) / systemd --user (linux)
- 9/9 vitest tests pass; end-to-end /health + send/check round-trip verified
- CI split: existing ci.yml/release.yml renamed to *-dotnet.yml with path
  filters, new ci-node.yml and release-node.yml publish to Gitea npm registry
- install.ps1 / install.sh bootstrap one-liners at repo root; homebrew/
  contains a tap formula template
- README install section reordered: npm path primary, dotnet publish secondary

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

node/src/types/node-windows.d.ts

@@ -0,0 +1,21 @@
+declare module "node-windows" {
+  export interface ServiceOpts {
+    name: string;
+    description?: string;
+    script: string;
+    nodeOptions?: string[];
+    workingDirectory?: string;
+  }
+
+  export class Service {
+    constructor(opts: ServiceOpts);
+    on(
+      event: "install" | "uninstall" | "alreadyinstalled" | "start" | "stop" | "error",
+      cb: (err?: unknown) => void,
+    ): void;
+    install(): void;
+    uninstall(): void;
+    start(): void;
+    stop(): void;
+  }
+}