feat(cli): scaffold @claudemesh/cli MCP client package (stubs)

The user-facing tool. Two invocation modes:
  - `claudemesh mcp`           → MCP server (stdio), consumed by Claude Code
  - `claudemesh <subcommand>`  → human CLI

Layout:
  apps/cli/
  ├── package.json       bin: { claudemesh: ./src/index.ts }
  ├── README.md          install + usage
  └── src/
      ├── index.ts       dispatcher (mcp | install | join | list | leave | --help)
      ├── env.ts         CLAUDEMESH_BROKER_URL, CONFIG_DIR, DEBUG
      ├── mcp/
      │   ├── server.ts  MCP stdio server with 5 tools
      │   ├── tools.ts   tool schemas (send_message, list_peers,
      │   │              check_messages, set_summary, set_status)
      │   └── types.ts
      ├── ws/client.ts   broker connection (stub for 15b)
      ├── state/config.ts ~/.claudemesh/config.json (joined meshes + keys)
      └── commands/
          ├── install.ts print `claude mcp add ...` instruction
          ├── join.ts    parse ic://join/... (stub, Step 17)
          ├── list.ts    show joined meshes
          └── leave.ts   remove mesh from local config

Tool stubs return "not connected, run `claudemesh join <invite-link>`"
errors until 15b wires the WS client.

Verified:
- `bun src/index.ts --help` → prints usage
- `bun src/index.ts install` → prints MCP add command with resolved path
- `bun src/index.ts list` → "No meshes joined yet"
- `bun src/index.ts mcp` (via stdin) → returns tools/list with all 5 tools

Deps: @modelcontextprotocol/sdk, ws, libsodium-wrappers, zod.
Lockfile regenerated in the same commit per claudemesh-3's flag —
avoids breaking Coolify's --frozen-lockfile deploys.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/cli/src/mcp/server.ts

@@ -0,0 +1,86 @@
+/**
+ * MCP server (stdio transport) for @claudemesh/cli.
+ *
+ * Invoked by Claude Code as a stdio subprocess. Exposes the 5 tools
+ * in tools.ts. In this 15a scaffold, all tools return a "not
+ * connected" response; 15b will wire them to a live WS broker
+ * connection.
+ */
+
+import { Server } from "@modelcontextprotocol/sdk/server/index.js";
+import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
+import {
+  ListToolsRequestSchema,
+  CallToolRequestSchema,
+} from "@modelcontextprotocol/sdk/types.js";
+import { TOOLS } from "./tools";
+import { loadConfig } from "../state/config";
+
+const NOT_CONNECTED = {
+  content: [
+    {
+      type: "text" as const,
+      text: "claudemesh: not yet connected to broker. Run `claudemesh join <invite-link>` to join a mesh, then restart your Claude Code session. (Broker client wiring lands in Step 15b — scaffold only for now.)",
+    },
+  ],
+  isError: true,
+};
+
+const INSTRUCTIONS = `You are connected to a claudemesh — a peer-to-peer network of other Claude Code sessions.
+
+Use these tools to coordinate with peers on demand. Each mesh is a trust boundary; messages are E2E-encrypted and routed through a shared broker.
+
+Available tools:
+- send_message: send a direct or channel message
+- list_peers: see who else is in your meshes and their status
+- check_messages: pull undelivered messages (normally pushed automatically)
+- set_summary: describe what you're working on (visible to peers)
+- set_status: manually override your presence (idle/working/dnd)
+
+When you receive an inbound message (channel notification), respond promptly — like answering a knock on the door. The sender is waiting on you.`;
+
+export async function startMcpServer(): Promise<void> {
+  // Load config so we know which meshes the user has joined.
+  const config = loadConfig();
+
+  const server = new Server(
+    { name: "claudemesh", version: "0.1.0" },
+    {
+      capabilities: { tools: {} },
+      instructions: INSTRUCTIONS,
+    },
+  );
+
+  server.setRequestHandler(ListToolsRequestSchema, async () => ({
+    tools: TOOLS,
+  }));
+
+  server.setRequestHandler(CallToolRequestSchema, async (req) => {
+    const { name } = req.params;
+    // Stubs: all tools return "not connected" until 15b.
+    if (config.meshes.length === 0) {
+      return {
+        content: [
+          {
+            type: "text" as const,
+            text: `claudemesh: no meshes joined yet. Run \`claudemesh join <invite-link>\` to join one.`,
+          },
+        ],
+        isError: true,
+      };
+    }
+    switch (name) {
+      case "send_message":
+      case "list_peers":
+      case "check_messages":
+      case "set_summary":
+      case "set_status":
+        return NOT_CONNECTED;
+      default:
+        throw new Error(`Unknown tool: ${name}`);
+    }
+  });
+
+  const transport = new StdioServerTransport();
+  await server.connect(transport);
+}