Introduce `tg_watchdog_heartbeat_every` to emit periodic INFO heartbeats.
Add cumulative diagnostics counters and richer logging for watchdog probes,
restart reasons, and disconnect‑flap triggers. Update defaults and tests
accordingly.
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.
vvzvlad