bugfix: fix threading races and concurrency in moonrakerComm/RepeatedTimer

[gmmcosta15]

• Feature
• Bug fix
• Code refactor
• Documentation

Description

• Move connected, connecting, _reconnect_count, callback_table from class-level to __init__ to prevent shared state across instances.
• Add _state_lock (RLock) and _request_lock guarding all reads/writes to those vars.
• Fix mutable default argument params={} → params=None in send_request.
• Fix unbound super() in OneShotTokenError.
• Guard _retry_timer with None check before stopTimer/startTimer; stop existing timer in try_connection before creating a new one (prevents orphaned threads).
• Replace sendEvent → postEvent for safe cross-thread event delivery.
• Wrap json.loads in try/except; use .get() on all external response dicts.
• Add klippy startup/disconnected retry cap (30 attempts) to prevent infinite reconnect loop.
• Add join(timeout=self.timeout+1) on _wst to avoid indefinite block on shutdown.
• Fix RepeatedTimer: inverted stopEvent semantics (set=stop, clear=running).

Motivation

The WebSocket layer had multiple threading races and incorrect cross-thread event dispatch causing UI freezes and crashes on Pi hardware. RepeatedTimer had inverted stop-event logic causing timers to never stop correctly. These are the root-cause fixes for the most severe class of bugs in #200.