feat(config): Config loading and merging

config/dtype/git.py

@@ -1,13 +1,13 @@
-from typing import TypedDict
+from typing import Optional, TypedDict
 
 
 class ArchMgrGitConfig(TypedDict):
-    creds: ArchMgrGitCredsConfig
-    repos: list[ArchMgrGitRepoConfig]
+    creds: Optional[ArchMgrGitCredsConfig]
+    repos: Optional[list[ArchMgrGitRepoConfig]]
 
 
 class ArchMgrGitCredsConfig(TypedDict):
-    manager: str
+    manager: Optional[str]
 
 
 class ArchMgrGitRepoConfig(TypedDict):