priv: reject colons in bind paths to avoid nspawn delimiter confusion

hive-priv/src/main.rs

@@ -359,9 +359,11 @@ fn agent_flake_ref(name: &str) -> String {
 fn validate_bind_path(path: &str) -> Result<()> {
     if path.is_empty()
         || !path.starts_with('/')
-        || path.bytes().any(|b| b == 0 || b == b'\n' || b == b'"')
+        || path.bytes().any(|b| b == 0 || b == b'\n' || b == b'"' || b == b':')
     {
-        bail!("invalid bind path {path:?}: must be an absolute path with no newlines, null bytes, or double-quotes");
+        bail!(
+            "invalid bind path {path:?}: must be an absolute path with no colons, newlines, null bytes, or double-quotes"
+        );
     }
     Ok(())
 }