Build 265: a way in for passkey servers, seamless streaming, and reader themes

[briarrrn]

Build 265 is on TestFlight now. It's a big one, covering everything since 258.

Signing in through a passkey provider. If your server signs in through a passkey-only provider such as Pocket ID, the app used to open the sign-in page and go nowhere. iOS refuses passkey prompts inside an app's embedded page, and the provider blamed you for cancelling. You didn't. The app now explains this the moment it happens and names the way in: your provider's alternative sign-in, where a typed login code completes the whole flow. The sign-in screen also has a new "Passkeys, SSO and magic links" link explaining every method, and the wiki's Signing in page carries the same steps.

Streaming audiobooks no longer stutter every 15 minutes. The sign-in ticket used to expire mid-play, and renewing it was audible. Each piece of audio now fetches its own fresh ticket, so there's nothing left to rebuild and nothing to hear.

Reader themes. Pick a preset from the grid or edit your own. Colours are kept readable automatically, and your existing theme carries over on its own. The appearance sheet was reorganized around them.

Also in this build:

• Books you add on the server show up when you pull to refresh, without force-quitting the app.
• Very large libraries load to the end instead of silently stopping partway.
• A review written offline is kept and sent when you reconnect.
• The first big library sync says what it's doing instead of looking hung.
• The page holds still while you swipe a book closed.
• The book page's more menu no longer closes itself the moment it opens.
• Fixed the app being killed when you lock the screen mid-sync, and search indexing on big libraries using too much memory.
• Sorting large libraries is snappier.

Please update and tell me how the passkey sign-in and streaming behave for you. Those two are the paths I most want checked.