feat(build): add comprehensive Claude Code executable build system

Add complete build infrastructure for creating single-file Claude Code executables
across all supported platforms using Bun's native compilation features.

- **Cross-platform builds**: Support for Linux (glibc/musl), macOS (Intel/ARM), Windows
- **CPU optimization variants**: Modern (AVX2+) and baseline (pre-2013) CPU support
- **Embedded assets**: All executables include yoga.wasm and ripgrep binaries
- **Optimized builds**: Minification and sourcemaps for production-ready binaries

package.json

@@ -6,6 +6,11 @@
   "scripts": {
     "dev": "vite",
     "build": "tsc && vite build",
+    "build:executables": "bun run scripts/fetch-and-build.js",
+    "build:executables:current": "bun run scripts/fetch-and-build.js current",
+    "build:executables:linux": "bun run scripts/fetch-and-build.js linux",
+    "build:executables:macos": "bun run scripts/fetch-and-build.js macos",
+    "build:executables:windows": "bun run scripts/fetch-and-build.js windows",
     "preview": "vite preview",
     "tauri": "tauri"
   },