fix: auto-adopt the only candidate instead of popping a single-option picker

When there's exactly one tunnel to resume, inquire still rendered the
prompt with a forced '>' marker on the lone row and arrow keys were
no-ops. The terminal cursor sat on the '? Resume which tunnel?' line —
visually it looked like the selector hadn't moved 'to the correct line'
because there was no other line to move to. The picker only earns its
keep when there's a choice to make.

Short-circuit at one candidate: print 'Resuming the only tunnel ...'
naming the hostname and id, return it directly. The >1 case still pops
the picker, where arrow-key movement was verified working under pty
with cursor-position+selected-index alignment.

Author: drewr

cli/src/main.rs

@@ -987,6 +987,22 @@ async fn pick_tunnel_interactive(
     if candidates.is_empty() {
         return Ok(None);
     }
+
+    // Single candidate: no point prompting. The selection marker would sit
+    // on the only row and arrow keys would be no-ops, which looks like a
+    // wedge from the user's perspective (terminal cursor still on the
+    // prompt line). Just adopt it and tell the user what happened.
+    if candidates.len() == 1 {
+        let only = candidates.remove(0);
+        let host = only
+            .hostnames
+            .first()
+            .map(String::as_str)
+            .unwrap_or(only.id.as_str());
+        println!("Resuming the only tunnel in this project: {host} (id: {})", only.id);
+        return Ok(Some(only));
+    }
+
     // Most-likely-relevant first: tunnels you previously enabled (have an
     // advertisement) bubble up before disabled ones.
     candidates.sort_by(|a, b| {