interactive: Host/View entry menu, clipboard copy, player picker

Bare `pixelpass` now opens a dialoguer-driven Host/View menu instead of
going straight to host mode. Host path copies the ticket to the system
clipboard via arboard with silent print-only fallback. View path
prompts for the ticket, then after the local listener binds prompts
mpv-vs-VLC and spawns it detached (setsid + null stdio) so the player
survives pixelpass exiting.

Headless invocations (`pixelpass <ticket>`, `pixelpass --repair`)
unchanged. Per spec at ~/Documents/pixelpass-interactive-mode-spec.md.

src/host/mod.rs

@@ -30,7 +30,8 @@ pub async fn run(opts: HostOpts) -> Result<()> {
 
     let addr = endpoint.addr();
     let ticket = EndpointTicket::new(addr);
-    print_host_banner(&ticket, display, &opts);
+    let clipboard_ok = opts.interactive && copy_to_clipboard(&ticket.to_string());
+    print_host_banner(&ticket, display, &opts, clipboard_ok);
 
     let result = accept_loop(&endpoint, display, &opts, cancel.clone()).await;
 
@@ -93,7 +94,12 @@ async fn handle_peer(
     Ok(())
 }
 
-fn print_host_banner(ticket: &EndpointTicket, display: DisplayServer, opts: &HostOpts) {
+fn print_host_banner(
+    ticket: &EndpointTicket,
+    display: DisplayServer,
+    opts: &HostOpts,
+    clipboard_ok: bool,
+) {
     eprintln!();
     eprintln!("┌─ PixelPass · host ─────────────────────────────────────────");
     eprintln!("│  display server : {display:?}");
@@ -101,7 +107,13 @@ fn print_host_banner(ticket: &EndpointTicket, display: DisplayServer, opts: &Hos
     eprintln!("│  bitrate / fps  : {} kbps @ {} fps", opts.bitrate, opts.framerate);
     eprintln!("│  hw encode      : {}", if opts.no_hwencode { "off" } else { "auto (VAAPI if available)" });
     eprintln!("│");
-    eprintln!("│  Share this ticket with your viewer:");
+    if clipboard_ok {
+        eprintln!("│  Your share code has been copied to your clipboard.");
+        eprintln!("│  Send it to your viewer. (If clipboard didn't work, the");
+        eprintln!("│  code is also shown below for manual copy.)");
+    } else {
+        eprintln!("│  Share this ticket with your viewer:");
+    }
     eprintln!("│");
     eprintln!("│      pixelpass {ticket}");
     eprintln!("│");
@@ -111,6 +123,16 @@ fn print_host_banner(ticket: &EndpointTicket, display: DisplayServer, opts: &Hos
     eprintln!();
 }
 
+fn copy_to_clipboard(text: &str) -> bool {
+    match arboard::Clipboard::new().and_then(|mut cb| cb.set_text(text.to_owned())) {
+        Ok(()) => true,
+        Err(e) => {
+            tracing::warn!("clipboard copy failed: {e}");
+            false
+        }
+    }
+}
+
 fn capture_summary(opts: &HostOpts) -> String {
     let mut bits = vec![if opts.window { "window" } else { "fullscreen" }.to_string()];
     if let Some(app) = &opts.app {