Initial: ContinuousTransponder wrapper for Kogger USBL

High-level Python wrapper around the upstream cosma-tech/kogger_acousticAntenna
driver. Configures a Kogger acoustic antenna as a permanent slave transponder
in a single start() call: address filter, echo filter, optional TDMA sync slot,
permanent response window, and Python callbacks for each ping received.

No modification to the upstream driver — only composes existing public methods
in the right order. Snapshot of upstream driver included read-only under driver/
for reference.

Includes:
- transponder_continu.py (302 lines): the wrapper class + CLI
- examples/auv_slave.py (79 lines): usage example with logging
- README.md: design rationale, usage, multi-AUV TDMA, watchdog, hardware wiring
- driver/: snapshot of cosma-tech/kogger_acousticAntenna at commit 1b539f9
  ('Add index slot for multi pinger', 2025-03-11)

Built for Cosma context (USV master + N AUVs slaves) following the design
conversation in Discord #ping-pong-ping (2026-04-27). See poulpe/ping-pong-ping
on Gitea for the interactive demo of the protocol.

driver/log_merge_nav_usbl.py

@@ -0,0 +1,111 @@
+#! /usr/bin/env python
+import csv
+import glob
+import os
+from datetime import datetime
+import sys
+
+def merge_log_files(nav_file, usbl_file, output_file):
+    """
+    Merges navigation and USBL log files into a single CSV file with the format:
+    timestamp,data,value
+
+    Args:
+        nav_file (str): Path to the navigation log CSV file.
+        usbl_file (str): Path to the USBL log CSV file.
+        output_file (str): Path to the output merged CSV file.
+    """
+    try:
+        all_lines = []
+
+        # Read the navigation log
+        with open(nav_file, 'r') as f:
+            reader = csv.reader(f)
+            header = next(reader)  # Skip header
+            for row in reader:
+                all_lines.append(row)
+        # Remove last line if broken
+        if len(all_lines[-1]) != 3:
+            all_lines.pop()
+
+        # Read the USBL log
+        with open(usbl_file, 'r') as f:
+            reader = csv.reader(f)
+            for row in reader:
+                timestamp, data, value = row
+                if timestamp == "timestamp":
+                    # Remove timestamp header if present (in merge from other merge)
+                    continue
+                data = 'usbl_' + data
+                if data == 'usbl_ID':
+                    value = str(int(float(value)))
+                all_lines.append([timestamp, data, value])
+        if len(all_lines[-1]) != 3:
+            all_lines.pop()
+
+        # Sort by timestamp
+        all_lines.sort(key=lambda x: datetime.strptime(x[0], '%Y-%m-%d %H:%M:%S.%f'))
+
+        # Write to CSV
+        with open(output_file, 'w', newline='') as f:
+            writer = csv.writer(f)
+            writer.writerow(['timestamp', 'data', 'value'])
+            writer.writerows(all_lines)
+            
+        print(f"Successfully merged {nav_file} and {usbl_file} into {output_file}")
+
+    except Exception as e:
+        print(f"An error occurred: {e}")
+
+if __name__ == "__main__":
+    try:
+        if len(sys.argv) == 2:
+            input_file_path = sys.argv[1]
+            target_directory = os.path.dirname(input_file_path)
+            if target_directory == "":
+                target_directory = "."
+
+            filename_only = os.path.basename(input_file_path)
+            base_name = "_".join(filename_only.split('_')[:3])
+            if not base_name:
+                 raise ValueError("Could not parse base name from filename.")
+            print(f"Processing specific files for base name: {base_name}")
+
+            nav_log_file = os.path.join(target_directory, f'{base_name}_navigation_log.csv')
+            usbl_csv_file = os.path.join(target_directory, f'{base_name}_usbl_csv.csv')
+            output_filename = os.path.join(target_directory, f'{base_name}_merged_log.csv')
+
+            print(f"Merging {nav_log_file} and {usbl_csv_file} to {output_filename}")
+            merge_log_files(nav_log_file, usbl_csv_file, output_filename)
+
+        elif len(sys.argv) == 3:
+            nav_file = sys.argv[1]
+            usbl_file = sys.argv[2]
+
+            nav_basename = os.path.splitext(os.path.basename(nav_file))[0]
+            usbl_basename = os.path.splitext(os.path.basename(usbl_file))[0]
+            
+            output_dir = os.path.dirname(nav_file)
+            if not output_dir:
+                output_dir = "."
+            
+            output_filename = os.path.join(output_dir, f"{nav_basename}_{usbl_basename}_merged.csv")
+
+            print(f"Merging {nav_file} and {usbl_file} to {output_filename}")
+            merge_log_files(nav_file, usbl_file, output_filename)
+
+        else:
+            print("Error: Invalid number of arguments. Please provide 1 or 2 arguments.")
+            print("")
+            print("Usage:")
+            print("  1 argument: python log_merge_nav_usbl.py <any_log_file_from_session>")
+            print("     (This will find navigation and usbl logs from the same session and merge them)")
+            print("  2 arguments: python log_merge_nav_usbl.py <navigation_log_file.csv> <usbl_log_file.csv>")
+            print("     (This will merge the two specified files)")
+            sys.exit(1)
+
+    except FileNotFoundError as e:
+        print(f"Error: File not found: {e}")
+    except Exception as e:
+        print(f"An unexpected error occurred: {e}")
+