feat(esp32-s3-lcd-43): add touch test harness and coordinate transformation

AGENTS.md

@@ -168,6 +168,17 @@ Use `#pragma once` (not `#ifndef` guards).
 | `status` | Print state + memory info |
 | `reboot` | Restart device |
 
+**Touch Test Commands** (ESP32-S3-LCD-4.3 only):
+| Command | Action |
+|---------|--------|
+| `TEST:touch X Y press` | Inject synthetic press at raw panel coords (X,Y) |
+| `TEST:touch X Y release` | Inject synthetic release at raw panel coords (X,Y) |
+| `TEST:touch clear` | Clear test mode (required between touch sequences) |
+
+Note: The S3 touch panel is rotated 180° relative to the display. Use raw panel coordinates:
+- Display (100,140) → Raw (700, 340)
+- Display (700,140) → Raw (100, 340)
+
 ## Monitor Daemon and Logging
 
 The build system includes a Python-based monitor agent that provides JSON logging and command pipes.