Problem

mer init crashes with FileNotFound because Zig 0.16's process.run() doesn't search PATH by default.

Error

error: FileNotFound
std/Io/Threaded.zig:15104:9 in processSpawnPosix

Solution

Add a resolveInPath() helper that searches PATH for the zig executable before calling process.run().

Acceptance Criteria

• mer init myapp works when zig is in PATH
• Uses full absolute path to zig executable
• Graceful fallback if zig not found

Priority

P0 - Blocking bug