fix(npm): download binaries during postinstall

The npm package was missing the actual binary download step - users got
wrapper scripts pointing to non-existent binaries.

Changes:
- postinstall.js now downloads correct binary from GitHub releases
- Added vestige.js wrapper for CLI binary
- Exposed both vestige-mcp and vestige commands in package.json
- Updated README with troubleshooting, storage info, CLI docs
- Added .gitignore for downloaded binaries

Fixes fresh install issues where Claude Desktop couldn't attach and
vestige CLI wasn't found.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/vestige-mcp-npm/bin/vestige-mcp.js

@@ -2,18 +2,30 @@
 
 const { spawn } = require('child_process');
 const path = require('path');
+const fs = require('fs');
 const os = require('os');
 
 const platform = os.platform();
-const arch = os.arch();
-
 const binaryName = platform === 'win32' ? 'vestige-mcp.exe' : 'vestige-mcp';
-const binaryPath = path.join(__dirname, '..', 'bin', binaryName);
+const binaryPath = path.join(__dirname, binaryName);
+
+if (!fs.existsSync(binaryPath)) {
+  console.error('Error: vestige-mcp binary not found.');
+  console.error(`Expected at: ${binaryPath}`);
+  console.error('');
+  console.error('Try reinstalling: npm install -g @vestige/mcp');
+  process.exit(1);
+}
 
 const child = spawn(binaryPath, process.argv.slice(2), {
   stdio: 'inherit',
 });
 
+child.on('error', (err) => {
+  console.error('Failed to start vestige-mcp:', err.message);
+  process.exit(1);
+});
+
 child.on('exit', (code) => {
   process.exit(code ?? 0);
 });

packages/vestige-mcp-npm/bin/vestige.js

@@ -0,0 +1,31 @@
+#!/usr/bin/env node
+
+const { spawn } = require('child_process');
+const path = require('path');
+const fs = require('fs');
+const os = require('os');
+
+const platform = os.platform();
+const binaryName = platform === 'win32' ? 'vestige.exe' : 'vestige';
+const binaryPath = path.join(__dirname, binaryName);
+
+if (!fs.existsSync(binaryPath)) {
+  console.error('Error: vestige CLI binary not found.');
+  console.error(`Expected at: ${binaryPath}`);
+  console.error('');
+  console.error('Try reinstalling: npm install -g @vestige/mcp');
+  process.exit(1);
+}
+
+const child = spawn(binaryPath, process.argv.slice(2), {
+  stdio: 'inherit',
+});
+
+child.on('error', (err) => {
+  console.error('Failed to start vestige:', err.message);
+  process.exit(1);
+});
+
+child.on('exit', (code) => {
+  process.exit(code ?? 0);
+});