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

requirements.txt

@@ -1,8 +1,8 @@
-aiogram>=3.0.0
-python-dotenv>=1.0.0
-aiohttp-socks>=0.8.0
-sqlalchemy>=2.0.0
-aiosqlite>=0.19.0
-faster-whisper>=1.1.0
-httpx[socks]
-boto3>=1.34.0
+aiogram==3.20.0
+python-dotenv==1.1.0
+aiohttp==3.12.4
+aiohttp-socks==0.10.1
+sqlalchemy==2.0.40
+aiosqlite==0.21.0
+faster-whisper==1.1.1
+boto3==1.37.25