add config discovery

src/zona/config.py

@@ -0,0 +1 @@
+

src/zona/layout.py

@@ -23,13 +23,25 @@ class Layout:
         return layout
 
 
+def find_config(start: Path | None = None) -> Path | None:
+    current = (start or Path.cwd()).resolve()
+
+    for parent in [current, *current.parents]:
+        candidate = parent / "zona.yml"
+        if candidate.is_file():
+            return candidate
+    return None
+
+
 def discover_layout(
     cli_root: Path | None = None, cli_output: Path | None = None
 ) -> Layout:
     if cli_root:
         root = cli_root
     else:
-        # TODO: config based discovery
-        # We just set cwd for now
-        root = Path(".")
+        config = find_config(cli_root)
+        if config:
+            root = config.parent
+        else:
+            root = Path.cwd()
     return Layout.from_input(root, cli_output)