emulator fast mode

[ignaciotcrespo]

Emulator fast mode & kill emulator

Summary

• Add fast mode for launching emulators: headless, no audio, Quick Boot snapshots, and host GPU acceleration — significantly faster than cold boot, ideal for previewing without the emulator UI
• Fast mode is enabled by default and can be toggled with f in the device picker
• Add kill emulator command (x): opens a picker listing running emulators to stop them, especially useful for headless emulators that have no window to close

Changes

• internal/adb/adb.go — StartEmulator now supports fast mode flags (-no-window -no-audio -gpu auto); added ListRunningEmulators(), KillEmulator(), and AVD name resolution via adb emu avd name
• internal/ui/app.go — Fast mode toggle state, kill picker modal with navigation and enter-to-kill, emulatorKilledMsg handling, x keybind
• internal/ui/view.go — Fast mode checkbox (white text) in device picker, kill emulator picker modal
• internal/ui/render.go — Added x kill emu to help bar
• README.md — Documented both features: key bindings, feature list, new sections with examples

Test plan

• Press d to open device picker — fast mode checkbox should show [✓] by default
• Press f in picker to toggle fast mode off/on
• Select an AVD with fast mode on — emulator should launch headless (no window)
• Select an AVD with fast mode off — emulator should launch with GUI
• Press x with running emulators — picker should list them with AVD name and serial
• Select an emulator and press Enter — it should be killed and removed from device list
• Press x with no running emulators — should show "No running emulators found"