Pin messages on the phone (GRYT-1678)

[sivert-io]

The phone half of pinned messages. The server half is server#281, out as 1.10.56-beta.2. The desktop half is client#807.

What's in it

• Pin and Unpin in the hold menu. You get them with manage_messages in a channel, or as anyone in a DM. MLS messages and unsent ones don't get them.
• "pinned" under a pinned message, next to "edited".
• A pin button in the channel header. It opens a drawer listing the pins, newest first. Tapping one scrolls to it if it's loaded, and otherwise says it's further back.
• useMessages listens for chat:pinned, so a pin made on another device shows straight away.

Not verified on a device yet. Typecheck and the test suite pass (1395). In the simulator, the dev build kept reopening an old test server, and I couldn't switch it to the local pins server with injected taps. Someone needs to hold a message on a server running 1.10.56-beta.2 before this merges.

Don't merge before the server is on latest. On a stable server the Pin item does nothing.

🤖 Generated with Claude Code

[sivert-io]

Checked on the iPhone 17 Pro simulator: dev client on this branch's Metro, against a local server at main (pins, 98f93e6). I was an owner in a #general seeded with 120 messages, two of them pinned (3 and 115).

• The pin button shows in the channel header, and "pinned" shows under 115.
• The pins drawer lists 115 then 3, newest first, with sender and time.
• Tapping 115 while scrolled up at message 59 scrolls back to it.
• Tapping 3, which isn't loaded, shows "That message is further back than what's loaded".
• The hold menu on 110 offers Pin. Tapping it stored the pin on the server (checked in the DB), and "pinned" showed under 110 straight away.
• Holding 110 again offers Unpin. Tapping it cleared it on the server, and the drawer dropped it.

Not checked: a DM, a member without manage_messages (the item should be hidden), and Android.

Server 1.10.56 with pins is on stable now, so the "don't merge before the server is on latest" note no longer applies.