fix: fetch the Actor from the API root in get_streamed_log() on last_run() clients

[vdusek]

get_streamed_log() and get_status_message_watcher() built the Actor client from the run client's _base_url. On actor(...).last_run() or task(...).last_run() that is the parent's URL, so the Actor lookup hit /v2/acts/<X>/acts/<actId>, got a 404, and the logger name had no Actor name. They now use the API root, like iterate_dataset_items().

Closes: #1137

✍️ Drafted by Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.46%. Comparing base (53a9954) to head (6a0e950).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1143      +/-   ##
==========================================
+ Coverage   95.43%   95.46%   +0.03%     
==========================================
  Files          61       61              
  Lines        5935     5935              
==========================================
+ Hits         5664     5666       +2     
+ Misses        271      269       -2     

Flag	Coverage Δ
integration	90.95% <ø> (+0.15%)	⬆️
unit	88.91% <ø> (+0.03%)	⬆️

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