Files pane plays through the player bar, once

The pane drew its own <audio controls> for a downloaded file, and its
onplay also started the player bar, so one click played the same file
twice at once. The pane now has a play button (with the file's type
icon, like the other rows) that hands that exact file to the player
bar, the only player. play() takes the file, so another of an item's
files starts from its top instead of resuming the first. Dead CSS for
the pane's <audio> removed.

Test: play in the Files pane leaves one <audio> on the page, the bar's.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0173mGu6rK18Ne7UGTwAaVJV

CHANGELOG.md

@@ -61,6 +61,8 @@ The long form, with what was wrong before and how it was found, is in
 
 ### Fixed
 
+- Playing a file from the Files pane played it twice at once, in the pane and in the player bar.
+  The pane has a play button now, and the player bar is the only player.
 - The password box in Manage users was white in the dark theme.
 - An item with no date showed a stray dot in its details.
 - Escape did not close a dialog while the cursor was in one of its boxes, so Add feed, which opens