Fix ssh/scp/sftp for containers running as a uid without passwd entry

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/src/sshkeys.rs

@@ -126,7 +126,10 @@ pub fn write_files(app: &App, user: &User, s: &SshSettings) -> Result<()> {
     chmod(&host_cfg, 0o600)?;
     for (bin, config) in [(bin_dir(&home), format!("'{}'", host_cfg.display())), (home.join(SANDBOX_BIN), "\"$HOME/.ssh/config-sandbox\"".to_string())] {
         std::fs::create_dir_all(&bin)?;
-        for (name, real) in [("ssh", "/usr/bin/ssh"), ("scp", "/usr/bin/scp"), ("sftp", "/usr/bin/sftp")] {
+        for name in ["ssh", "scp", "sftp"] {
+            // The image's /usr/local/bin wrappers cope with a uid without passwd entry.
+            let local = format!("/usr/local/bin/{name}");
+            let real = if Path::new(&local).exists() { local } else { format!("/usr/bin/{name}") };
             let p = bin.join(name);
             std::fs::write(&p, format!("#!/bin/sh\nexec {real} -F {config} \"$@\"\n"))?;
             chmod(&p, 0o755)?;