Anonymous, opt-out usage telemetry and configurable desktop terminals

3.4.2 adds a small anonymous usage beacon so we can see which platforms, surfaces, and models to prioritise, and gives the desktop terminal real shell profiles. The telemetry is privacy-first and easy to turn off.

New

• Anonymous usage telemetry. On session start Empryo sends one tiny beacon, version, OS, surface (TUI / headless / hearth / desktop), install method, provider + public model name, agent mode, terminal, runtime, theme, and a random install id used only to count distinct installs. Never prompts, file paths, code, keys, IPs, or anything that could identify you. Turn it off any time: set "telemetry": false in your config, or DO_NOT_TRACK=1 / EMPRYO_TELEMETRY=0 in the environment. A one-time notice explains this on first run.
• Desktop terminal shell profiles. The embedded terminal now supports VS Code-style shell profiles, pick your shell and args per platform instead of being stuck with the default login shell.

Fixed

• The desktop terminal failed to spawn in packaged builds, the bundled app now resolves the shell correctly, so the terminal opens in the shipped DMG / installer as it does in dev.