feat: Bun single-file executable distribution (#819)

* feat: add Bun single-file executable distribution

- Add 7 platform packages for standalone CLI binaries
- Add bin/platform.js for shared platform detection
- Add bin/oh-my-opencode.js ESM wrapper
- Add postinstall.mjs for binary verification
- Add script/build-binaries.ts for cross-compilation
- Update publish workflow for multi-package publishing
- Add CI guard against @ast-grep/napi in CLI
- Add unit tests for platform detection (12 tests)
- Update README to remove Bun runtime requirement

Platforms supported:
- macOS ARM64 & x64
- Linux x64 & ARM64 (glibc)
- Linux x64 & ARM64 (musl/Alpine)
- Windows x64

Closes #816

* chore: remove unnecessary @ast-grep/napi CI check

* chore: gitignore compiled platform binaries

* fix: use require() instead of top-level await import() for Bun compile compatibility

* refactor: use static ESM import for package.json instead of require()

bin/oh-my-opencode.js

@@ -0,0 +1,80 @@
+#!/usr/bin/env node
+// bin/oh-my-opencode.js
+// Wrapper script that detects platform and spawns the correct binary
+
+import { spawnSync } from "node:child_process";
+import { createRequire } from "node:module";
+import { getPlatformPackage, getBinaryPath } from "./platform.js";
+
+const require = createRequire(import.meta.url);
+
+/**
+ * Detect libc family on Linux
+ * @returns {string | null} 'glibc', 'musl', or null if detection fails
+ */
+function getLibcFamily() {
+  if (process.platform !== "linux") {
+    return undefined; // Not needed on non-Linux
+  }
+  
+  try {
+    const detectLibc = require("detect-libc");
+    return detectLibc.familySync();
+  } catch {
+    // detect-libc not available
+    return null;
+  }
+}
+
+function main() {
+  const { platform, arch } = process;
+  const libcFamily = getLibcFamily();
+  
+  // Get platform package name
+  let pkg;
+  try {
+    pkg = getPlatformPackage({ platform, arch, libcFamily });
+  } catch (error) {
+    console.error(`\noh-my-opencode: ${error.message}\n`);
+    process.exit(1);
+  }
+  
+  // Resolve binary path
+  const binRelPath = getBinaryPath(pkg, platform);
+  
+  let binPath;
+  try {
+    binPath = require.resolve(binRelPath);
+  } catch {
+    console.error(`\noh-my-opencode: Platform binary not installed.`);
+    console.error(`\nYour platform: ${platform}-${arch}${libcFamily === "musl" ? "-musl" : ""}`);
+    console.error(`Expected package: ${pkg}`);
+    console.error(`\nTo fix, run:`);
+    console.error(`  npm install ${pkg}\n`);
+    process.exit(1);
+  }
+  
+  // Spawn the binary
+  const result = spawnSync(binPath, process.argv.slice(2), {
+    stdio: "inherit",
+  });
+  
+  // Handle spawn errors
+  if (result.error) {
+    console.error(`\noh-my-opencode: Failed to execute binary.`);
+    console.error(`Error: ${result.error.message}\n`);
+    process.exit(2);
+  }
+  
+  // Handle signals
+  if (result.signal) {
+    const signalNum = result.signal === "SIGTERM" ? 15 : 
+                      result.signal === "SIGKILL" ? 9 :
+                      result.signal === "SIGINT" ? 2 : 1;
+    process.exit(128 + signalNum);
+  }
+
+  process.exit(result.status ?? 1);
+}
+
+main();