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/commands/leave.ts

@@ -0,0 +1,25 @@
+/**
+ * `claudemesh leave <slug>` — remove a mesh from local config.
+ *
+ * Does NOT (yet) notify the broker. In 15b+ this will send a
+ * best-effort revoke request before removing the entry.
+ */
+
+import { loadConfig, saveConfig } from "../state/config";
+
+export function runLeave(args: string[]): void {
+  const slug = args[0];
+  if (!slug) {
+    console.error("Usage: claudemesh leave <slug>");
+    process.exit(1);
+  }
+  const config = loadConfig();
+  const before = config.meshes.length;
+  config.meshes = config.meshes.filter((m) => m.slug !== slug);
+  if (config.meshes.length === before) {
+    console.error(`claudemesh: no joined mesh with slug "${slug}"`);
+    process.exit(1);
+  }
+  saveConfig(config);
+  console.log(`Left mesh "${slug}". Remaining: ${config.meshes.length}`);
+}