fix: handle websocket errors gracefully in comfy run

[bigcat88]

When using comfy run --workflow with long-running workflows, websocket errors (timeouts, connection drops) would crash with unhandled Python tracebacks. This made it hard to understand what went wrong and how to fix it.

Added exception handling in execute() for WebSocketTimeoutException and general WebSocketException/ConnectionError. Timeout errors now print a clear message with a hint to increase --timeout. Connection drops print the specific error reason. Both exit cleanly with code 1 and properly clean up the progress bar.

Tested against a local ComfyUI instance with forced timeout (0.001s), forced connection drop (socket shutdown mid-execution), and normal workflow completion. All three paths produce clean output instead of tracebacks.

Fixes #200

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main     #384      +/-   ##
==========================================
+ Coverage   63.89%   66.59%   +2.70%     
==========================================
  Files          33       33              
  Lines        3700     3706       +6     
==========================================
+ Hits         2364     2468     +104     
+ Misses       1336     1238      -98     

Files with missing lines	Coverage Δ
comfy_cli/command/run.py	66.19% <100.00%> (+49.03%)	⬆️

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