Introduce an active watchdog that probes the Telegram client to detect
zombie sessions and restart them in‑process. Add configurable disconnect
flap detection with a sliding window to trigger restarts after repeated
disconnects. New environment variables and config entries are added, and
the Kurigram dependency is now version‑pinned.
Replace MagicMock based text/caption mocks with a lightweight StrWithHtml
subclass that provides the required `.html` property while behaving like a
regular string. This fixes length and strip checks in the parser and
simplifies test setup. Also adds default proxy settings to mock_config for
test completeness.