[utkuhalis]

The Mac launcher's Discord "Playing …" status, on Windows and Linux.

What it does:

• With Discord open, the profile shows the running game and for how long. A game Discord knows (its public detectable list, cached for a week) shows as itself, with "AnyPS5 Launcher · Windows" or "· Linux" under it. Any other game shows under AnyPS5.
• In a party it says "In a party" with the party's size (of 8), even with no game.
• A "Join on AnyTogether" button opens the party's join code page. The party's leader gets a code made for the button when none works, but not after stopping the code themselves. Family rules that turn off public matchmaking also stop it.
• Settings › Behaviour gets two switches after Show Hidden Trophies, as on the Mac: "Show the game you play on Discord" and "Show a Join button on Discord". Both are on by default and kept per profile.
• Cleared when the game stops, the setting goes off, or the launcher quits.

How it talks to Discord:

• Linux: the Unix socket discord-ipc-0 to 9 in the runtime folder (and its Flatpak and Snap folders), the temporary folder, then /tmp.
• Windows: the named pipe \.\pipe\discord-ipc-0 to 9 through kernel32 (CreateFileW, WriteFile, ReadFile, PeekNamedPipe for a read timeout). A silent Discord never holds the launcher up.
• ANYPS5_DISCORD_APP_ID puts another application in place of AnyPS5's own, and set but empty turns the status off.

Not in this PR: the Mac also offers the share play it hosts for the button. The Port's share play (now on main) has no join codes, so only the party's code counts.

Tests: frame codec, game names, the activity JSON and button limits, the join plan, the application ID, a fake Discord in memory, and a real Unix socket fake Discord (not on Windows). A UI test covers the settings rows, the party's activity and button, the switch clearing it, and a stopped code not made again.

The Windows named pipe is compiled by the Windows build here but has not been run against a real Discord.