Player: a sleep timer, and AirPlay in the app (#429)

The sleep timer pauses after 5 minutes to an hour, fading out over the
last ten seconds. In the iOS app the phone's player keeps the time:
with the screen locked the web view is frozen, and a timer in the page
would not fire until the app was opened again. A browser plays on in a
background tab, so there the page keeps it.

The app says at ready what it does itself ({t:"host", can}), so a page
deployed ahead of the app falls back to its own timer and shows no
AirPlay button an older app would ignore. This deploy order problem
came up with #425.

AirPlay opens AVRoutePickerView by pressing its button from code; there
is no API to present it. On iOS 27 the picker opens on the button's
primary action, not touch-up, so that is what is sent, with touch-up
for versions that have nothing on it. The simulator has no AirPlay
devices and never showed the picker, so this is unverified until it
runs on a phone.

On a phone the player's one line left the title two letters wide once
the two controls were added, so the title takes the top line and the
controls flank play below it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- A sleep timer in the player: 5 minutes to an hour, then playback fades out and pauses. In the iOS app the phone keeps the time, so it works with the screen locked; the app and Safari also get an AirPlay button. On a phone the title has the player's top line to itself, with the controls either side of play below it (#429).
 - In the iOS app, Keep on this device keeps the episode on the phone, where the app's own player plays it with no connection; until now the app had no Keep button (#425).
 - An episode kept on this device says so in its row of the list, On this device, not only in its files (#413).
 - Keep an episode on this device to listen offline: the button beside Play on a downloaded episode keeps the file, without its dead air if DeadAir shortens it for you, and it then plays from the device whether you are online or not, with your place sent once the connection is back. Press it again to take it off; signing out takes everything off (#412).