Fix sendspin metadata sending wrong progress when paused (#3250)

Fix sendspin metadata sending wrong progress when paused (#3250)

* Fix sendspin metadata sending wrong progress when paused

Two issues caused the progress bar in sendspin clients to show wildly
incorrect values (e.g. 795:54 / 04:23) after reconnecting to a paused
stream:

1. playback_speed was hardcoded to 1000 (normal) and never set to 0
   when paused, so the server kept advancing progress.

2. Used PlayerMedia.corrected_elapsed_time which always interpolates
   elapsed time regardless of playback state (adding hours of wall-
   clock time while paused).  Switched to Player.corrected_elapsed_time
   which only interpolates during PLAYING.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* fix(sendspin): preserve metadata progress when paused

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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: Maxim Raznatovski <nda.mr43@gmail.com>