Prevents shipping hooks with JavaScript SyntaxError (like the duplicate const cwd declaration that caused PostToolUse errors for all users in v1.25.1). The build script now validates each hook file's syntax via vm.Script before copying to dist/. If any hook has a SyntaxError, the build fails with a clear error message and exits non-zero, blocking npm publish. Refs #1107, #1109, #1125, #1161