Add episode recording functionality and enhance serial communication handling

- Introduced record_episode.py for capturing ESP32 IMU data and RealSense images.
- Added SwitchChangeDetector and SwitchLevelController for managing recording triggers.
- Enhanced ESP32Bridge with new methods for reading samples and latest packets.
- Updated verify.py and visualise.py to improve serial communication stability.
- Modified .gitignore to include dataset, csv, and png directories.

verify.py

@@ -57,10 +57,33 @@ def read_serial_samples(port, baud, seconds=None, max_samples=None, max_gap_ms=1
     last_t_ms = None
     elapsed_s = 0.0
     bad_delta_count = 0
-    start = time.monotonic()
 
-    with serial.Serial(port, baud, timeout=1) as ser:
+    ser = serial.Serial()
+    ser.port = port
+    ser.baudrate = baud
+    ser.timeout = 0.05
+    ser.write_timeout = 0.05
+
+    # Avoid unwanted ESP32 auto-reset / boot-mode toggling.
+    ser.dtr = False
+    ser.rts = False
+
+    ser.open()
+
+    try:
+        # Some USB-UART adapters may still change line states during open().
+        ser.dtr = False
+        ser.rts = False
+
+        ser.reset_input_buffer()
+        ser.reset_output_buffer()
+
         print(f"Reading {port} at {baud} baud...", file=sys.stderr)
+        print("Waiting for ESP32 main.py startup...", file=sys.stderr)
+        time.sleep(4.0)
+
+        # Start timing after ESP32 startup wait.
+        start = time.monotonic()
 
         while True:
             if seconds is not None and time.monotonic() - start >= seconds:
@@ -110,6 +133,9 @@ def read_serial_samples(port, baud, seconds=None, max_samples=None, max_gap_ms=1
                 if max_samples is not None and len(samples) >= max_samples:
                     break
 
+    finally:
+        ser.close()
+
     if bad_delta_count:
         print(f"Ignored {bad_delta_count} abnormal packet time delta(s).", file=sys.stderr)