refactor: review fixes and code improvements

- Add shared proxy module (bot/utils/proxy.py) to eliminate duplicate SOCKS5 parsing
- Fix AI client: escape HTML before Markdown→HTML conversion, unify timeouts,
  make health check optional and disabled by default, handle 429 retries
- Fix ai.py: correct forwarded message handling (aiogram 3.x forward_origin),
  pass relevant summaries via extra_system_content
- Fix dialogue.py: only respond to Astra's messages, use system context instead
  of prompt injection, answer on the limit message before phase transition
- Fix voice.py: load Whisper model in thread pool, safe WAV path generation
- Improve database.py: composite indexes, Boolean is_active, upsert file_id cache,
  add context cleanup helper
- Update weather.py and yadisk_download.py to use shared proxy connector
- Update yadisk.py: validate URL before cache clear, add download size limit,
  wrap sync file ops in to_thread
- Reuse S3 client via lru_cache
- Update setup_commands with /aiclear and /aiuser
- Update README, Dockerfile (Python 3.11), docker-compose (mount models)
- Pin dependency versions, remove unused httpx[socks]
- Add basic pytest tests for layout converter and voice normalization

tests/test_layout_converter.py

@@ -0,0 +1,23 @@
+import pytest
+
+from bot.utils.layout_converter import convert_layout
+
+
+@pytest.mark.parametrize(
+    "input_text, expected",
+    [
+        ("gbdj", "пиво"),
+        ("rjytxyj!", "конечно!"),
+        ("Ghbdtn", "Привет"),
+        ("123", "123"),
+        ("", ""),
+        ("qwerty", "йцукен"),
+    ],
+)
+def test_convert_layout(input_text: str, expected: str) -> None:
+    assert convert_layout(input_text) == expected
+
+
+def test_convert_layout_preserves_case() -> None:
+    assert convert_layout("QWERTY") == "ЙЦУКЕН"
+    assert convert_layout("QwErTy") == "ЙцУкЕн"