Fix for Tauri app not loading .env file with dotenvy. Use when: (1) Environment
variables return "not set" errors in Tauri commands, (2) dotenvy::from_filename()
fails with relative paths like "../../.env", (3) API keys or config work locally
but not in Tauri app, (4) GhostClient::from_env() or similar fails with missing
env vars. The fix is that `cargo tauri dev` runs with CWD at project root, not
at ui/src-tauri, so use ".env" not "../../.env".