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()

packages/linux-x64/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "oh-my-opencode-linux-x64",
+  "version": "0.0.0",
+  "description": "Platform-specific binary for oh-my-opencode (linux-x64)",
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/code-yeongyu/oh-my-opencode"
+  },
+  "os": ["linux"],
+  "cpu": ["x64"],
+  "libc": ["glibc"],
+  "files": ["bin"],
+  "bin": {
+    "oh-my-opencode": "./bin/oh-my-opencode"
+  }
+}