feat(paths): auto-create config dir on daemon startup

ensure_dirs() now creates config_dir alongside state_dir and log_dir,
so first daemon run materializes $XDG_CONFIG_HOME/xy/servers/ — making
it obvious where to drop server .kdl files.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/xy/src/paths.rs

@@ -30,6 +30,7 @@ impl Paths {
     }
 
     pub fn ensure_dirs(&self) -> std::io::Result<()> {
+        std::fs::create_dir_all(&self.config_dir)?;
         std::fs::create_dir_all(&self.state_dir)?;
         std::fs::create_dir_all(&self.log_dir)?;
         Ok(())
@@ -45,4 +46,24 @@ mod tests {
         let p = Paths::resolve().unwrap();
         assert!(p.pidfile.starts_with(&p.state_dir));
     }
+
+    #[test]
+    fn ensure_dirs_creates_all_paths() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+
+        let paths = Paths {
+            config_dir: root.join("config/xy/servers"),
+            state_dir: root.join("state/xy"),
+            log_dir: root.join("state/xy/logs"),
+            socket: root.join("run/xy.sock"),
+            pidfile: root.join("state/xy/xy.pid"),
+        };
+
+        paths.ensure_dirs().unwrap();
+
+        assert!(paths.config_dir.is_dir());
+        assert!(paths.state_dir.is_dir());
+        assert!(paths.log_dir.is_dir());
+    }
 }