Support Herdr protocol 22

[powerfooI]

Goal

Track Herdr's upcoming protocol 22 (post-0.8.2) so Herdr Studio keeps working after the next Herdr release.

Scope

• Handle the redesigned handshake: ClientMessage::Hello was replaced by TerminalHello; launch_mode, requested_encoding, and keybindings were removed (server/src/bridge/thin-client.ts, server/src/bridge/protocol-compat.ts)
• Handle workspace.close requiring close_group: true when linked-worktree workspaces are open (introduced in protocol 21, web/src/store.ts closeWorkspace)
• Reject unknown newer protocols with a clear error instead of silently mis-decoding (protocols 14-22 supported)
• OSC 52 clipboard relay on protocol 22+: verified from Herdr master source that ServerMessage::Clipboard is routed only to foreground endpoint-shell clients, which direct-terminal connections can never be. The relay is now skipped on protocol 22+ with an explicit warning instead of idling silently; clipboard sync returns with the endpoint-protocol migration.
• Verify end-to-end against a real Herdr build with protocol 22 once the next preview/stable ships (handshake, terminal stream, workspace close)
• Migrate to Herdr's stable endpoint protocol (generation 1) to restore clipboard sync and stop chasing the private bincode protocol per release

Notes

• Herdr v0.8.2 (protocol 20) remains the supported stable target; protocol 21/22 support is forward-looking and verified against wire-format and server-routing diffs plus unit tests, not a live Herdr 0.9.x server yet.
• Merge can happen before the next Herdr release: older Herdr servers are unaffected, and newer-than-22 now fails with a clear error.