feat(npm): Add npm package distribution support

Added npm package wrapper to enable installation via npm while
maintaining the Deno binary distribution model.

New Files:
- package.json: npm package configuration with binary wrapper
- bin/spark-wrapper.js: Detects platform and executes correct binary
- scripts/install-binary.js: Downloads appropriate binary on npm install
- .npmignore: Excludes source files from npm package
- npmextra.json: npm extra configuration

Updated:
- readme.md: Added npm installation instructions

How It Works:
1. User runs: npm install -g @serve.zone/spark
2. Postinstall script (install-binary.js) downloads the correct
   pre-compiled binary for the user's platform from Gitea releases
3. Binary is cached in dist/binaries/
4. Wrapper script (spark-wrapper.js) executes the binary when user
   runs 'spark' command

Supported via npm:
- Linux (x64, ARM64)
- macOS (Intel, Apple Silicon)
- Windows (x64)

This maintains the benefits of Deno compilation (no runtime deps)
while providing familiar npm-based installation for users who prefer it.

bin/spark-wrapper.js

@@ -0,0 +1,108 @@
+#!/usr/bin/env node
+
+/**
+ * SPARK npm wrapper
+ * This script executes the appropriate pre-compiled binary based on the current platform
+ */
+
+import { spawn } from 'child_process';
+import { fileURLToPath } from 'url';
+import { dirname, join } from 'path';
+import { existsSync } from 'fs';
+import { platform, arch } from 'os';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+/**
+ * Get the binary name for the current platform
+ */
+function getBinaryName() {
+  const plat = platform();
+  const architecture = arch();
+
+  // Map Node's platform/arch to our binary naming
+  const platformMap = {
+    'darwin': 'macos',
+    'linux': 'linux',
+    'win32': 'windows'
+  };
+
+  const archMap = {
+    'x64': 'x64',
+    'arm64': 'arm64'
+  };
+
+  const mappedPlatform = platformMap[plat];
+  const mappedArch = archMap[architecture];
+
+  if (!mappedPlatform || !mappedArch) {
+    console.error(`Error: Unsupported platform/architecture: ${plat}/${architecture}`);
+    console.error('Supported platforms: Linux, macOS, Windows');
+    console.error('Supported architectures: x64, arm64');
+    process.exit(1);
+  }
+
+  // Construct binary name
+  let binaryName = `spark-${mappedPlatform}-${mappedArch}`;
+  if (plat === 'win32') {
+    binaryName += '.exe';
+  }
+
+  return binaryName;
+}
+
+/**
+ * Execute the binary
+ */
+function executeBinary() {
+  const binaryName = getBinaryName();
+  const binaryPath = join(__dirname, '..', 'dist', 'binaries', binaryName);
+
+  // Check if binary exists
+  if (!existsSync(binaryPath)) {
+    console.error(`Error: Binary not found at ${binaryPath}`);
+    console.error('This might happen if:');
+    console.error('1. The postinstall script failed to run');
+    console.error('2. The platform is not supported');
+    console.error('3. The package was not installed correctly');
+    console.error('');
+    console.error('Try reinstalling the package:');
+    console.error('  npm uninstall -g @serve.zone/spark');
+    console.error('  npm install -g @serve.zone/spark');
+    process.exit(1);
+  }
+
+  // Spawn the binary with all arguments passed through
+  const child = spawn(binaryPath, process.argv.slice(2), {
+    stdio: 'inherit',
+    shell: false
+  });
+
+  // Handle child process events
+  child.on('error', (err) => {
+    console.error(`Error executing spark: ${err.message}`);
+    process.exit(1);
+  });
+
+  child.on('exit', (code, signal) => {
+    if (signal) {
+      process.kill(process.pid, signal);
+    } else {
+      process.exit(code || 0);
+    }
+  });
+
+  // Forward signals to child process
+  const signals = ['SIGINT', 'SIGTERM', 'SIGHUP'];
+  signals.forEach(signal => {
+    process.on(signal, () => {
+      if (!child.killed) {
+        child.kill(signal);
+      }
+    });
+  });
+}
+
+// Execute
+executeBinary();