fix: allow mining directories without local mempalace.yaml

When no mempalace.yaml or mempal.yaml exists in the source directory,
return a default config (wing = directory name, room = general) instead
of calling sys.exit(1). This lets users mine any directory into their
palace without requiring init first.

Closes #14.

tests/test_miner.py

@@ -6,7 +6,7 @@ from pathlib import Path
 import chromadb
 import yaml
 
-from mempalace.miner import mine, scan_project, status
+from mempalace.miner import load_config, mine, scan_project, status
 from mempalace.palace import NORMALIZE_VERSION, file_already_mined
 
 
@@ -52,6 +52,20 @@ def test_project_mining():
         shutil.rmtree(tmpdir, ignore_errors=True)
 
 
+def test_load_config_uses_defaults_when_yaml_missing():
+    tmpdir = tempfile.mkdtemp()
+    try:
+        project_root = Path(tmpdir).resolve()
+        config = load_config(str(project_root))
+
+        assert isinstance(config, dict)
+        assert "wing" in config
+        assert "rooms" in config
+        assert config["wing"] == project_root.name
+    finally:
+        shutil.rmtree(tmpdir)
+
+
 def test_scan_project_respects_gitignore():
     tmpdir = tempfile.mkdtemp()
     try: