Split experiments from tests

The tests/ directory held 50 laboratory programs and no tests. They model
channels, run hundreds of repetitions and write CSV, PNG and reports;
calling that a test suite blocked introducing a real one, because any
pytest run would have collected the labs and re-executed every
experiment.

- move all 50 lab programs to experiments/ with git mv, preserving history
- rewrite the 38 cross-imports between labs from tests.labNNN to
  experiments.labNNN
- leave tests/ empty for actual fast checks of protocol/
- point quick_gate and the hook at the new layout and add experiments/ to
  the syntax sweep
- update the paths quoted in the Lab042 specification and the verifier
  agent definition

This also defuses the import-time work finding without touching 41 files:
the labs still create directories and write files on import, but nothing
imports them now except the gate, which does so deliberately.

Gate passes: syntax clean, protocol imports, 15 lab modules import, 2
functional suites run.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

experiments/lab001_utf8_russian.py

@@ -0,0 +1,61 @@
+"""
+Lab001, часть 2.
+Русский текст, символы, байты и кодировка UTF-8.
+
+Цель:
+1. Увидеть разницу между количеством символов и количеством байтов.
+2. Посмотреть, сколько байтов занимает каждая русская буква.
+3. Восстановить исходный текст из байтов.
+"""
+
+# Исходное сообщение
+message = "ПРИВЕТ SDR"
+
+# Преобразование текста в байты UTF-8
+encoded_message = message.encode("utf-8")
+
+# Обратное преобразование байтов в текст
+decoded_message = encoded_message.decode("utf-8")
+
+
+print("Исходный текст:")
+print(message)
+
+print("\nКоличество символов:")
+print(len(message))
+
+print("\nКоличество байтов UTF-8:")
+print(len(encoded_message))
+
+print("\nОбъект bytes:")
+print(encoded_message)
+
+print("\nВсе байты в десятичном виде:")
+print(list(encoded_message))
+
+print("\nПодробно по каждому символу:")
+
+for character in message:
+    character_bytes = character.encode("utf-8")
+
+    decimal_bytes = list(character_bytes)
+
+    binary_bytes = " ".join(
+        f"{byte:08b}" for byte in character_bytes
+    )
+
+    print(
+        f"{character!r:>4} "
+        f"→ байтов: {len(character_bytes)} "
+        f"→ числа: {decimal_bytes} "
+        f"→ биты: {binary_bytes}"
+    )
+
+print("\nВосстановленный текст:")
+print(decoded_message)
+
+# Автоматические проверки
+assert decoded_message == message
+assert len(encoded_message) >= len(message)
+
+print("\nПроверка пройдена: русский текст восстановлен без ошибок.")