Initial import: keyrelay, a WiFi-controlled USB HID keyboard

Browser or terminal controller drives an ESP32-S3 that acts as a Logitech
G815 into a target machine running no software. Disarmed by default; arming
requires the passphrase, the board button, or the serial console, and every
fail-safe path cancels in-flight work.

- src/: firmware with pure, host-testable modules (keystate, proto, text,
  ws_codec, sha1), the WebSocket control server, and the served page
- tests/: host suites for the pure modules, relayctl parity, and page JS
- tools/: relayctl terminal controller, serial console, bootloader helper,
  and an evdev target watcher
- platformio.ini: bridge (USB HID) and console (no-HID) environments
- README.md: single source of truth for behaviour, protocol and safety

LLM-Generated: true

.gitignore

@@ -0,0 +1,21 @@
+# PlatformIO
+.pio/
+.pioenvs
+.piopm
+
+# host test build output (tests/run_tests.sh recreates it)
+tests/build/
+
+# python
+__pycache__/
+*.py[cod]
+
+# editors
+*.swp
+.DS_Store
+
+# never commit a passphrase, a capture, or a recording of what was typed
+*.env
+token
+*.capture
+*.log