feat(client/windows): per-host clipboard toggle

The bridge landed always-on whenever the host permitted it; sharing a
clipboard is a trust decision about a specific host, so it needs to be
opted into. Mirrors the Apple client's per-host model
(StoredHost.clipboardSync, "Share clipboard with this host") rather than a
global switch: KnownHost::clipboard_sync, toggled from the host card's
overflow menu, default off.

The session binary resolves the stored flag itself in session_params, so a
direct connect and the console's own launches honor the same decision
without every caller having to remember to pass it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/linux/src/cli.rs

@@ -352,6 +352,7 @@ pub fn headless_add_host(target: &str) -> glib::ExitCode {
             paired: false,
             last_used: None,
             mac: Vec::new(),
+            clipboard_sync: false,
         });
     }
     match known.save() {